# Mastermind Meets The Dolmar PS-6100



## Mastermind (Mar 9, 2014)

Dolmar's version of the stratifed chainsaw engine.......check it out.


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## Mastermind (Mar 9, 2014)




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## Mastermind (Mar 9, 2014)




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## Mastermind (Mar 9, 2014)




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## RedFir Down (Mar 9, 2014)

Cant wait to see more Randy!!!!

This saw really caught my eye when I started reading about it, Thank you sir!


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## Mastermind (Mar 9, 2014)

That's all I have for tonight. I'll be porting it tomorrow......then after work, I'll post more pics.


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## XSKIER (Mar 9, 2014)

That Reed valved stratification port might really turn out to be something! 

Great saw, sweet deal.


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## fordf150 (Mar 9, 2014)

Can't wait to see how this turns out


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## CR888 (Mar 9, 2014)

Good to see its business as usual and Randy is keeping the 'interesting' factor alive around here. He always does detailed interesting builds and answers everyones questions as best he can. Thanx 4 choosing another model that l'm sure will we would all like to know a little more about.


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## mweba (Mar 9, 2014)

This saw is outside the box guys. Very interesting stuff from Dolmar.


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## Mastermind (Mar 9, 2014)

Yeah Bob. I tore it down to see what it was about.......now I'm gonna put it back together and run it with just muffler work.

I may play with this one a bit.


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## Chris-PA (Mar 10, 2014)

Very interesting - real curious how the reed valve strato port works out, and what the stock timing numbers look like.

I'm betting it has a very short duration on the normal intake.


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## Mastermind (Mar 10, 2014)

Right you would be Chris.

These are opening points, measured from TDC....

Ex: 105.5°
In: 71°
Tr: 130°


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## Chris-PA (Mar 10, 2014)

That gives them almost 60deg of case compression angle, assuming the reed valves have closed the strato ports before the normal intake port closes. What is the opening angle of the strato port (ignoring the reed valve)?


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## cat-face timber (Mar 10, 2014)

As always your build threads are great!
I bet it is nice to work on a new CLEAN saw!


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## Mastermind (Mar 10, 2014)

Chris-PA said:


> That gives them almost 60deg of case compression angle, assuming the reed valves have closed the strato ports before the normal intake port closes. What is the opening angle of the strato port (ignoring the reed valve)?



The stratos have no opening point because of the reed valves. They use the upper transfers only. 



cat-face timber said:


> As always your build threads are great!
> *I bet it is nice to work on a new CLEAN saw!*



It is a fine thing........but it ain't always this way. 

I'm putting this thing back together with no mods at all. I wanna run it a little more. This design has me wondering if the muffler creates a scavenging effect and pulls the stratos open....if I gut the muffler will it kill the stratos??????


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## CapitaineHaddoc (Mar 10, 2014)

Is this saw comes apart as easily as 6400/7300/7900?


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## Chris-PA (Mar 10, 2014)

Mastermind said:


> The stratos have no opening point because of the reed valves. They use the upper transfers only.


I see it now - I thought they were still gated by a piston port but with the reeds added on, but they are entirely reed controlled.


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## HuskStihl (Mar 10, 2014)

Reed-valved stratos are cool n' stuff, but did you guys check out the awesome stamped chain direction indicator???!!! God how I wish all my saws had that!


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## HuskStihl (Mar 10, 2014)

Chris-PA said:


> I see it now - I thought they were still gated by a piston port but with the reeds added on, but they are entirely reed controlled.


OK, so the strato pathway is controlled exclusively by a shared linkage with the throttle, and the reed valves keep the port closed the rest of the time? The when the strato path is open, the air is sucked into the upper transfers and mixes with the "mix" coming up thru the case via the lower transfers? Is my brain on track with this? Thanks


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## Chris-PA (Mar 10, 2014)

There does not appear to be much opening area between the transfers and the case - just a pretty narrow slot?


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## Chris-PA (Mar 10, 2014)

HuskStihl said:


> OK, so the strato pathway is controlled exclusively by a shared linkage with the throttle, and the reed valves keep the port closed the rest of the time? The when the strato path is open, the air is sucked into the upper transfers and mixes with the "mix" coming up thru the case via the lower transfers? Is my brain on track with this? Thanks


Pretty much, but the mixing doesn't really happen until later when the fuel/air mix makes it up into the cylinder from the case. So air gets pulled in through the reed valve into the transfer runners on the way down to the case, and then flow reverses and it is pushed back up into the cylinder. Meanwhile, air has been pulled through the carb and into the case, and it gets up to the cylinder later.


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## HuskStihl (Mar 10, 2014)

Chris-PA said:


> Pretty much, but the mixing doesn't really happen until later when the fuel/air mix makes it up into the cylinder from the case. So air gets pulled in through the reed valve into the transfer runners on the way down to the case, and then flow reverses and it is pushed back up into the cylinder. Meanwhile, air has been pulled through the carb and into the case, and it gets up to the cylinder later.


So does the "clean air charge" hit the combustion chamber before the mix to push exhaust gasses out, or after to complete the burn on the downstroke?


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## Chris-PA (Mar 10, 2014)

HuskStihl said:


> So does the "clean air charge" hit the combustion chamber before the mix to push exhaust gasses out, or after to complete the burn on the downstroke?


The clean air gets there first, pushing the exhaust out. The rich fuel charge gets there late to prevent it from getting out the open exhaust port, but hopefully with enough time to mix thoroughly with the air already there. It's not supposed to be stratified at combustion, only on the way to the cylinder.

That is true for all stratos, but this one uses a reed valve on the air intake rather than a piston port. That means the strato port duration does not need to be symmetrical about TDC - it closes as soon as the pressure in the case rises which will likely be before the regular intake closes.

The case can begin to pressurize as soon as the intake closes, which will be sooner with this setup because it does not have to wait for a long duration strato port to close. So it should develop good transfer velocity. But reed valves have their own limitations, and I'm really curious how this works in practice.


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## HuskStihl (Mar 10, 2014)

Thank you very much for the explanation. I appreciate u'r taking the time!


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## Treespotter (Mar 10, 2014)

Mastermind said:


> now I'm gonna put it back together and run it with just muffler work.
> 
> I may play with this one a bit.


I've been playing around with it for a while now. And do you know what? I'm an arborist for thirty years now and this is the first saw that puts a smile on my face every time I get it out of the van. It's a hassle free saw that sometimes stalled when idleing the first 5 tanks of fuel. I hesitated pulling a screwdriver out to retune it but could prevent myself doing it. The stalling stopped and the saw runs great. I love it. 


Wolter


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## 7sleeper (Mar 10, 2014)

Been waiting a long time for this thread!

7


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## Mastermind (Mar 10, 2014)

I reassembled it today. Videoed it stock, then muffler modded, and then with the timing advanced. Jon and I are gonna top and piece down a large hickory that is in a spot that just dropping it ain't possible. I'll take this saw and put some more fuel thru it.....


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## bryanr2 (Mar 10, 2014)

opcorn: just something to do.


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## Plan-b (Mar 11, 2014)

Kawasaki uses reeds on the strato side in the tj27e engine, I think they started doing this around 2010.

Randy, are you finding it cold blooded as other stratos?


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## SawTroll (Mar 11, 2014)

HuskStihl said:


> Reed-valved stratos are cool n' stuff, but did you guys check out the awesome stamped chain direction indicator???!!! God how I wish all my saws had that!



It may of course mainly be a way to "work around" someone elses patents?


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## Trx250r180 (Mar 11, 2014)

seems like in the old days a thread like this would be on page 9 or 10 by now ........


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## fordf150 (Mar 11, 2014)

Its on page 9 elsewhere


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## HuskStihl (Mar 11, 2014)

Trx250r180 said:


> seems like in the old days a thread like this would be on page 9 or 10 by now ........


If it were a MS290 farm boss, it would be on 15 by now


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## tallguys (Mar 11, 2014)

SawTroll said:


> It may of course mainly be a way to "work around" someone elses patents?



A patent on chain direction? Just kidding.


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## Como (Mar 11, 2014)

I like the look of it, would match my Makita. Next size up.

Probably not many in my situation.


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## Chris-PA (Mar 11, 2014)

So this saw effectively has a hybrid reed valve/piston ported intake system. I'm not really sure what the advantage of that would be. The reed strato intake may open sooner and close sooner, but the ported intake is still symmetrical about TDC and held open. On the other hand with that big angle between the intake closing and the transfers opening, combined with a small case volume, the piston will be fighting against the case pressure for almost 1/3 of the down stroke - the energy going into compressing the case is not going out of the crankshaft. 

I dunno, I'm just a noob when it comes to this stuff but I'm not seeing the big advantage. Heck, if you count the reed valve as a moving part then has more moving parts than a piston ported strato.


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## Axlerod74 (Mar 11, 2014)

No left over room in the crankcase for anything.............


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## mtlogdog (Mar 11, 2014)

i like the look of the saw not as good lookn as 6400-7900 but still pretty


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## jimmycrackcorn (Mar 12, 2014)

Those stamping on those reeds look like Moto Tassinari. I put them in all my bikes & sleds. Their the best you can get, they definitely increases throttle response over the brittle stock ones. They also compliment intakes & exhausts. If those are them, it's good to see they didn't cheap out on inferior ones.

I know bikes & saws are two different animals but know that I look @the pics again, I'm having a hard time understanding how these reeds are incorporated into the intake. I also don't understand strato engines 100% & that could be the reason. TO ME, it looks like the reeds will only handle the air, unless the unit stacked on top of the carb handles fuel as well. Funny thing is, I tried to Google how this setup works so I wouldn't sound like an a$$ (too late) & this Mastermind thread is the only search result with info.. Nothing from Dolmar, nothing anywhere else. 

I'm curious to see how this works out, keep up the good work Randy.


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## buzz sawyer (Mar 12, 2014)

opcorn:


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## CR888 (Mar 12, 2014)

lts like everyone just got up and left this place!


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## griffonks (Mar 12, 2014)

I know, eerily silent in this AS thread. Many of the saw geeks have migrated. 

Sent from my SCH-R530C using Tapatalk


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## MGlazier28 (Mar 12, 2014)

I am eager to see how this new dolly performs, been a bit of a dolmar fan for a while now. Anxiously awaiting video!


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## SawTroll (Mar 12, 2014)

mtlogdog said:


> i like the look of the saw not as good lookn as 6400-7900 but still pretty



Definately not pretty - but that isn't what really counts anyway! 

On the heavy side for a 60cc saw, and an inboard clutch, aren't good signs regarding the handling though.



griffonks said:


> I know, eerily silent in this AS thread. Many of the saw geeks have migrated.


It just is pretty hard to be exited over that creation.....


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## Chris-PA (Mar 12, 2014)

griffonks said:


> I know, eerily silent in this AS thread. Many of the saw geeks have migrated.


In the equivalent thread on the other site there are about 2.5X as many posts, most of which are also content-free and/or unrelated to the saw. There really are not many people who are actually interested in the technical details of the way these things work.


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## mweba (Mar 12, 2014)

Chris-PA said:


> In the equivalent thread on the other site there are about 2.5X as many posts, most of which are also content-free and/or unrelated to the saw. There really are not many people who are actually interested in the technical details of the way these things work.



The people that understand such things usually don't reply. They read out of curiosity and occasionally help to explain how and why things work.

Although there are more posts of nonsense, the thread is still richer in valuable information.


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## Mastermind (Mar 12, 2014)

If it was all serious bidness I'd have left eons ago. 

I've not done anymore with this thing yet. I wanted to get a little run time on it then go back in. I'm porting 4 MS261s now.


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## Chris-PA (Mar 12, 2014)

Mastermind said:


> If it was all serious bidness I'd have left eons ago.
> 
> I've not done anymore with this thing yet. I wanted to get a little run time on it then go back in. I'm porting 4 MS261s now.


And I like to joke around too. Eventually you'll get caught up and get back to it, and then maybe we'll learn more about this system - it's the nature of having someone donate their time. It's not like I'll ever learn anything about this saw otherwise.

I'd personally prefer not having the thread accumulate 25 pages of fart jokes in the meantime, as it makes it difficult to look through later.


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## Mastermind (Mar 12, 2014)

This is the single most intriguing thing I've seen cross my work bench in a long time Chris. These saws all start to look alike after you've done a few hundred. This is something different.......


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## 7sleeper (Mar 12, 2014)

Mastermind said:


> This is the single most intriguing thing I've seen cross my work bench in a long time Chris. These saws all start to look alike after you've done a few hundred. This is something different.......


I heard the rumor a long time ago that at the dolmar plant there was a special masterplan and only the best of the best of designers, engineers, developers, etc. were admitted to the drawing board on how to construct a saw to intrigue "mastermind"....

 

7


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## Mastermind (Mar 12, 2014)

They done good, and stuff.


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## Chris-PA (Mar 12, 2014)

Mastermind said:


> This is the single most intriguing thing I've seen cross my work bench in a long time Chris. These saws all start to look alike after you've done a few hundred. This is something different.......


I can only imagine - doping out something different is what keep its interesting!


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## Termite (Mar 12, 2014)

Mastermind said:


> If it was all serious bidness I'd have left eons ago.
> 
> Yes I believe you, you like a little monkey bidness!
> 
> ...


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## fordf150 (Mar 12, 2014)

I have been into 2 of these saws and had them apart but never had the luxury of being able to try anything on one and porting one is above my pay grade. These saws definitely have some new/ different ideas in them and I am waiting rather impatiently to find out how much potential dolmar left behind or if this new design is maxed out as it is


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## nnero (Mar 12, 2014)

I am looking forwards to the video on this saw. It's now on the top of my list. It seems to be priced reasonable too.


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## Mastermind (Mar 12, 2014)

I had a guy from GA come up and pick up a saw. He just peeled out, so I'm working on these pics and videos now.


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## fastLeo151 (Mar 12, 2014)

Fact is dolmars are junk.... Everyone knows this right??


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## Mastermind (Mar 12, 2014)

This is where the strato ports enter the transfers area. 





Videos are uploading......


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## watsonr (Mar 12, 2014)

Knock Knock...
















Just kiddin.. Hey Randy, I sent you a present today


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## Mastermind (Mar 12, 2014)

Who's there?????

Thanks Randy....you're a great friend.


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## fordf150 (Mar 12, 2014)

fastLeo151 said:


> Fact is dolmars are junk.... Everyone knows this right??


They are almost as good as the the new homelite stuff...probably made in the same Chinese factory


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## Mastermind (Mar 12, 2014)

Jon ain't used to the new camera yet.


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## Mastermind (Mar 12, 2014)

Bone stock, new Oregon chisel chain.


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## watsonr (Mar 12, 2014)

Mastermind said:


> Who's there?????
> 
> Thanks Randy....you're a great friend.


Have to have a friend to be a friend... right back to you.

Cows go


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## Chris-PA (Mar 12, 2014)

What do you think of the opening between the transfers and the case? From the pictures it looks like a rather small area and an abrupt turn.


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## Mastermind (Mar 12, 2014)

I agree


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## Mastermind (Mar 12, 2014)




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## Chris-PA (Mar 12, 2014)

I counted 13s for each one?


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## CapitaineHaddoc (Mar 12, 2014)

The second video shows a second less!


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## Mastermind (Mar 12, 2014)

And that is why I normally wait till I'm done before I post videos. 

Drawing any conclusions from what is in these videos would be foolish......


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## CapitaineHaddoc (Mar 12, 2014)

Mastermind said:


> And that is why I normally wait till I'm done before I post videos.
> 
> Drawing any conclusions from what is in these videos would be foolish......



I'm just joking. I spoke of the time displayed by YouTube (45 vs 44). 

This topic is very interesting, especially as here in France, Dolmar saws are much cheaper than Stihl / Husky! I hesitate to take a 610 Beal for some time.


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## Mastermind (Mar 12, 2014)

I'm hesitant to add much outlet to the muffler before port work. On the 7900 it seems to hurt the engines torque to have the muffler opened too much. 

Baby steps........


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## CapitaineHaddoc (Mar 12, 2014)

Mastermind said:


> I'm hesitant to add much outlet to the muffler before port work. On the 7900 it seems to hurt the engines torque to have the muffler opened too much.
> 
> Baby steps........



But the 7900 muffler is not a SLR muffler, he's probably less restrictive thant this one, no?


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## Mastermind (Mar 12, 2014)

The 7900 and 7910 behave the same way in relation to muffler outlet......even after the restrictions inside the mufflers are removed on both. The port configurations and timing numbers are the same.....only the mufflers and the coils are really different. 

This 6100 is very similar to the 7900 in the layout and timing of the upper transfers. That makes me wonder is the outlet considerations should be thought about in the same manner.


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## Chris-PA (Mar 12, 2014)

Mastermind said:


> And that is why I normally wait till I'm done before I post videos.
> 
> Drawing any conclusions from what is in these videos would be foolish......


The only thing I concluded from the videos was that they are all about the same, therefore those mods don't appear to be the restriction - and I know you were not implying that, just starting to experiment. 

I don't know how the saw felt, but it doesn't sound like it is bogging, although that might just have been proper control and not letting it bog. The exhaust note was steady in all three videos and it chugged along nicely but didn't sound like it wanted to rev. Kinda like a reed valve saw?


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## 7sleeper (Mar 12, 2014)

Don't know for sure but it looks like there is a lot of dust in the air. Are you sure the chain is sharp?

Next question How do you like it(antivib, handling, etc.)? 

Thanks for the update & videos! 

7


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## RedFir Down (Mar 12, 2014)

No offense here but.... do you really think Randy would run a saw with a dull chain, especially since it is being videoed and put on the internet???
I mean the guys owns a Simington!!


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## 7sleeper (Mar 12, 2014)

No offense taken. It was just something I noticed. Maybe someone else noticed it also? Just because a chain is brand new doesn't mean anything. And Randy has already expressed his fondness for chain sharpening. Further no idea what type of wood it is. So I am just mentioning my observation, because I am used to different videos from Randy. If I'm wrong thats ok with me.

7


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## watsonr (Mar 12, 2014)

Cow go who?
No, cow go moo

Where DDS when you need him?


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## Mastermind (Mar 12, 2014)

The chain is a new loop of Oregon LGX


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## mweba (Mar 12, 2014)

Mastermind said:


> The chain is a new loop of Oregon LGX



Oregon sells chain dull these days? Lotta dust out da back.

Maybe it's rotten? Ya, that's it...rotten wood.

On the other hand. It could be seasoned hard wood...

Hell if I know.


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## jimmycrackcorn (Mar 12, 2014)

So the reeds don't handle fuel..? Anyone?


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## Mastermind (Mar 12, 2014)

Just air Jimmy.


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## fordf150 (Mar 12, 2014)

jimmycrackcorn said:


> So the reeds don't handle fuel..? Anyone?


Reeds are just on the strato so no fuel through them


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## jimmycrackcorn (Mar 12, 2014)

Mastermind said:


> Just air Jimmy.





fordf150 said:


> Reeds are just on the strato so no fuel through them



Thanks my dudes.. I understand it now, at least the intake aspect that is.. Y'all ever seen them used like that? I haven't.. But I've also been out of the power sports loop for a bit.


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## Mastermind (Mar 12, 2014)

This is a new animal for me. 

That oak is some two year old stuff that's pretty damn gnarly. I'll get a better piece before round two.....


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## CTYank (Mar 12, 2014)

Reportedly RedMax Stage 1 stratified scavenging used reed valves similarly. They did invent "strato" 2-strokes. So, this approach is certainly pretty main-stream stuff, with some history. Who knows how much was shared/licensed?
I was already interested in this saw some time back. Sorry, Troll.


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## procarbine2k1 (Mar 12, 2014)

Watching closely! I am happy to see Dolmar pumping out new saws. I would love to see more Dolmar dealers popping up, I figured more mom and pop shops would be looking into Dolmar that weren't happy with the whole Jonsered/Tilton thing, or ones that wanted to add to the *** brands they already offered.


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## HuskStihl (Mar 12, 2014)

The imbedded youtube videos blur the fast stuff so much the discharge always tends to look dusty to me. On my phone I can see a stream of big chips, on YouTube looks like a cloud of dust


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## mweba (Mar 12, 2014)

HuskStihl said:


> The imbedded youtube videos blur the fast stuff so much the discharge always tends to look dusty to me. On my phone I can see a stream of big chips, on YouTube looks like a cloud of dust


This man gets it.


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## Terry Syd (Mar 12, 2014)

Its been a while since I looked at the patents, but I recall the first strato design was a reed valve to the upper transfers. That design did not have a control valve to bring in the strato later, it operated all the time, even at idle.

Some of the Dolmar design may be an attempt to get around other patents.

The first thing I noticed when I saw the two intakes was how small the strato butterfly was in comparison to the carb. Perhaps the reeds allow the strato port to remain open much longer and the extra area of the ports isn't needed. Reeds tend to stay open much longer than you would think they should.

This is an interesting design, it kinda reminds me of the motorcycle engines that used a piston port design that had a 'floor' to the port that fed a reed valve. That design gave the engine more mid-range torque.

EDIT: I also noticed the transfer duration, from your figures it would be just 100 degrees. Also from the pictures it looks like the transfer ports may have emphasised a wider port to bring the time/area back up.


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## Chris-PA (Mar 12, 2014)

Terry Syd said:


> EDIT: I also noticed the transfer duration, from your figures it would be just 100 degrees. Also from the pictures it looks like the transfer ports may have emphasised a wider port to bring the time/area back up.


Also interesting is that the "blowdown" is fairly large, whereas with other stratos I've seen that angle is smaller than typical. Definitely some different stuff going on here.


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## mweba (Mar 12, 2014)

Terry Syd said:


> Its been a while since I looked at the patents, but I recall the first strato design was a reed valve to the upper transfers. That design did not have a control valve to bring in the strato later, it operated all the time, even at idle.
> 
> Some of the Dolmar design may be an attempt to get around other patents.
> 
> ...



I'm lazy sooo. I'll quote my thoughts on the port/reed timing design.

"I would assume the same applies for muffler and scavenge as any saw. Seams to me, the strato is drawn from bdc until the upper trans are closed off by the piston. Once that occurs, a fresh charge is on top when the intake opens at 71°. If my assumption is correct, the only real difference is the path of the strato charge. Doesn't travel through the piston as we are use to."

"The only time I can logically see a pressure below atmospheric in the upper trans is described in my previous post. . Now the standard strato uses a side piston port that open the same time of the intake. This draws low pressure through both at the same time but strato has less time open."

Digging this design as it makes changes to the flow pattern easier to manage than the typical Strato design.


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## mweba (Mar 12, 2014)

Chris-PA said:


> Also interesting is that the "blowdown" is fairly large, whereas with other stratos I've seen that angle is smaller than typical. Definitely some different stuff going on here.



I would assume the blow down is greater on this saw as the duration allowed for fresh air in the upper trans is much less than the typical design that opens starto and case volume at the same time.


Meaning less "clean" air needs to scavenge out.


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## Chris-PA (Mar 12, 2014)

mweba said:


> I would assume the blow down is greater on this saw as the duration allowed for fresh air in the upper trans is much less than the typical design that opens starto and case volume at the same time.
> 
> 
> Meaning less "clean" air needs to scavenge out.



Well, increasing that angle is one of the techniques used on a non-strato engine to reduce scavenging losses (reducing the time both ports are open). Everything tells me that the strato function on this saw is just less effective than piston ported strato systems - the little air valve and small looking strato runners, the bigger carb, the larger blowdown angle - at least from the point of view of reduced scavenging losses. The question is whether it has other advantages? If the strato system works well enough to meet the limits and it makes more power, well then good. But does it?

Also, the GZ4000 has a longer duration on the strato intake than on the regular intake, while numbers from others I've seen have the strato duration shorter. I have one with a strato duration of 163 and an intake of 144, and that runs quite nicely.


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## Terry Syd (Mar 12, 2014)

mweba said:


> Seams to me, the strato is drawn from bdc until the upper trans are closed off by the piston. Once that occurs, a fresh charge is on top when the intake opens at 71°.
> .



At BDC the transfers will still be flowing because of crankcase compression. However, once the transfers are closed, the crankcase can begin to create a low pressure to draw in the next charge. In the case of a straight piston port engine, there is a lag time between the transfers closing and the intake opening (say at 80 degrees BTDC). With the reeds, there will be no lag in induction, the reeds will begin to flow as soon as the pressure drops. There is also less pumping loss when the engine can actually breathe rather that fighting against an increasing low pressure below the piston.

The elimination of that lag time in the induction cycle is what gives a rotary valve engine such an advantage. A reed valve engine also has that advantage, unfortunately it also has the reeds obstructing the flow.

I do like this design, it appears to have some potential.


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## Chris-PA (Mar 12, 2014)

Terry Syd said:


> There is also less pumping loss when the engine can actually breathe rather that fighting against an increasing low pressure below the piston.


But doesn't it have to fight high pressure the way back down for a longer time, due to the reed closing sooner? The piston ported intake is still open, but that is a short duration.


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## mweba (Mar 12, 2014)

Terry Syd said:


> At BDC the transfers will still be flowing because of crankcase compression. However, once the transfers are closed, the crankcase can begin to create a low pressure to draw in the next charge. In the case of a straight piston port engine, there is a lag time between the transfers closing and the intake opening (say at 80 degrees BTDC). With the reeds, there will be no lag in induction, the reeds will begin to flow as soon as the pressure drops. There is also less pumping loss when the engine can actually breathe rather that fighting against an increasing low pressure below the piston.
> 
> The elimination of that lag time in the induction cycle is what gives a rotary valve engine such an advantage. A reed valve engine also has that advantage, unfortunately it also has the reeds obstructing the flow.
> 
> I do like this design, it appears to have some potential.


Did you read what I wrote?

At bdc the pressure is atmospheric and not flowing. The strato draws from bdc until trans close. At which point the case is filled.


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## Mastermind (Mar 12, 2014)

You fellers think too much.

I'm gonna go play some chess....


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## mweba (Mar 12, 2014)

Mastermind said:


> You fellers think too much.
> 
> I'm gonna go play some chess....


If I get a candy crush request.....


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## Terry Syd (Mar 13, 2014)

mweba said:


> Did you read what I wrote?
> 
> At bdc the pressure is atmospheric and not flowing. The strato draws from bdc until trans close. At which point the case is filled.



Yep, I read what you wrote.

Maybe some of you will remember when Timberwolf did some great velocity charts of the flow through the transfers. It showed maximum velocity in the transfers just before BDC and then the velocity slowly dropping until the transfer ports closed. The charts were taken at maximum horsepower, so they were after the point of maximum torque - or peak delivery ratio. That's why the charts showed that the flow into the cylinder continued right up until the transfers closed. (and is illustrative of why extra time/area for the transfers is used to increase top end power - to continue allowing the flow into the cylinder)

If he had taken the readings at the point of peak delivery ratio it would have shown the flow just coming to a stop as the transfers closed.

If he had taken the readings below peak torque it would have shown a reversal of the flow. The transfers would have been open too long and the rising piston would have begun to suck the mixture out of the cylinder and back down into the crankcase.


----------



## Mastermind (Mar 13, 2014)

I'm gonna take the linkage off of the strato butterfly....

Why all the overthinking this thing? It's so simple. 

Low pressure in the crankcase.......fresh air in the uppers......mix in the crankcase.

Pressure reverses........fresh air into the chamber.......mix follows.


----------



## Yukon Stihl (Mar 13, 2014)

watsonr said:


> Cow go who?
> No, cow go moo
> 
> Where DDS when you need him?


I herd he got tipped last night


----------



## Trx250r180 (Mar 13, 2014)

I have no idea what you guys are talking about ,but keep typing ,i may learn something


----------



## Chris-PA (Mar 13, 2014)

What I see now is an entirely conventional saw with a minimal-function strato system tacked on - just enough to avoid a cat or that stupid SLR thing, but not enough to derive any performance benefit like the Huskys. The implementation has pluses (small volume case, quad closed xrfs) and minuses (restrictive lower transfers and conservative port timing). 

As a conventional saw it should respond to conventional mods. Too bad, I was hoping there was something interesting here.


----------



## deye223 (Mar 13, 2014)

opcorn:


----------



## Treespotter (Mar 13, 2014)

Mastermind said:


> You fellers think too much.
> 
> I'm gonna go play some chess....


I think... I think you have a hard nut to crack on this one Mastermind! 
When my saw is properly run in by me I will probably drill out the holes in the inner part of the muffler a fraction more. Not removing it completely. A second step will be to open up the 'hood' that is covering the air filter and checking for excessive material in the air intake valves. 

Wolter


----------



## Mastermind (Mar 13, 2014)

I don't see it that way at all.......it's just an ordinary saw with an add on. And the add on just needs to be ignored so it can keep adding a puff of fresh air at the right time......


----------



## nnero (Mar 13, 2014)

What are you thoughts on the saw as a whole? Some say the weight an inboard will impact handling. Is the easy start system useful or just a gimmick? Does the master control switch function well? I know these aren't related to your business but are important in considering this saw. Thanks


----------



## Franny K (Mar 13, 2014)

Chris-PA said:


> What I see now is an entirely conventional saw with a minimal-function strato system tacked on - just enough to avoid a cat or that stupid SLR thing, but not enough to derive any performance benefit like the Huskys. The implementation has pluses (small volume case, quad closed xrfs) and minuses (restrictive lower transfers and conservative port timing).
> 
> As a conventional saw it should respond to conventional mods. Too bad, I was hoping there was something interesting here.



Why do you state small volume case? The crank is not filled or stuffed. I suppose having a 35mm stroke instead of a 36 like some other 59-60cc saws makes the crank cavity smaller. Or are you thinking the volume of various passages?


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## Mastermind (Mar 13, 2014)

nnero said:


> What are you thoughts on the saw as a whole? Some say the weight an inboard will impact handling. Is the easy start system useful or just a gimmick? Does the master control switch function well? I know these aren't related to your business but are important in considering this saw. Thanks



Seems well built.....

What easy start? I just pulled the rope.

I've not used it enough to comment on how it handles. 

I like the master control setup.


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## Chris-PA (Mar 13, 2014)

Franny K said:


> Why do you state small volume case? The crank is not filled or stuffed. I suppose having a 35mm stroke instead of a 36 like some other 59-60cc saws makes the crank cavity smaller. Or are you thinking the volume of various passages?


I should have said "relatively small" - they appeared to have made some attempt to reduce volume, but did not go to that much effort. I think the transfer entrance being restrictive is part of that, in that there are no scalloped out entrances.


----------



## nnero (Mar 13, 2014)

Mastermind said:


> What easy start? I just pulled the rope.



The website says it has a spring assist starter. You pull it once to "wind" the spring an then pull again to actually start. Thanks for all the info


----------



## fordf150 (Mar 13, 2014)

Dolmars easy start is a 2 part system. A spring in the recoil that acts similar to the stihl elastostart handle...and a ignition coil that fires a hotter spark at low RPM. not much to it. Very simple system that seems to work well especially on warm startups


----------



## Treespotter (Mar 13, 2014)

nnero said:


> Is the easy start system useful or just a gimmick?


On the 5105 it's a horrible gimmick that a lot of times works against you by throwing a sudden compression start in the equation. 
On the 6100 Dolmar has got it spot on. Every start is a smooth one. No sudden unsupported starts. 

Wolter


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## Great Smokies (Mar 13, 2014)

fordf150 said:


> Dolmars easy start is a 2 part system. A spring in the recoil that acts similar to the stihl elastostart handle...and a ignition coil that fires a hotter spark at low RPM. not much to it. Very simple system that seems to work well especially on warm startups


Having tried this saw, the system works very well to me. Doesn't lad up and release like others, which I hate. Just pulls easier at cold starts and at hot starts you just lift up, no need to yank it.


----------



## wigglesworth (Mar 14, 2014)

Chris-PA said:


> I'd personally prefer not having the thread accumulate 25 pages of fart jokes in the meantime, as it makes it difficult to look through later.




Not to call you out or nothing.....

But did you even look at the thread over there, or is that just speculation that in the 9 pages of that thread, there are 25 pages of "fart jokes"?

I'd much rather sift thru 25 pages of flaming fecal matter posts than view one single post filled with innacuracy, or stare at a "Is a 660 a good saw"thread, or watch 20 envious guys jump on a person for a craigslist buy that they didn't see first, so it must be "stolen" and are demanding the serial number, or see somebody list a saw for sale, then get beat down for asking too much, or selling it too cheap.... I could go on for days, but I won't.... You get the point.


----------



## Chris-PA (Mar 14, 2014)

wigglesworth said:


> Not to call you out or nothing.....
> 
> But did you even look at the thread over there, or is that just speculation that in the 9 pages of that thread, there are 25 pages of "fart jokes"?
> 
> I'd much rather sift thru 25 pages of flaming fecal matter posts than view one single post filled with innacuracy, or stare at a "Is a 660 a good saw"thread, or watch 20 envious guys jump on a person for a craigslist buy that they didn't see first, so it must be "stolen" and are demanding the serial number, or see somebody list a saw for sale, then get beat down for asking too much, or selling it too cheap.... I could go on for days, but I won't.... You get the point.


The comment was made that in the old days such a thread would be at 9 pages, and that on the other site it was - so I looked. Sure enough, 9 pages with half as many posts per page. In all it had 2.5 X the responses but not really any more content. The character of the filler was different, and if that's your cup of tea then enjoy it - it certainly doesn't matter to me as I won't be reading it. 

The things you find annoying here bug me too, but not nearly enough to want to hang out with the "I have a potty mouth" crowd. The weather will be turning soon and I won't have as much time for this distraction anyway.


----------



## mweba (Mar 14, 2014)

wigglesworth said:


> Not to call you out or nothing.....
> 
> But did you even look at the thread over there, or is that just speculation that in the 9 pages of that thread, there are 25 pages of "fart jokes"?
> 
> I'd much rather sift thru 25 pages of flaming fecal matter posts than view one single post filled with innacuracy, or stare at a "Is a 660 a good saw"thread, or watch 20 envious guys jump on a person for a craigslist buy that they didn't see first, so it must be "stolen" and are demanding the serial number, or see somebody list a saw for sale, then get beat down for asking too much, or selling it too cheap.... I could go on for days, but I won't.... You get the point.



You should see the look on guys faces when I ask to see their CCW to purchase a saw from me.


----------



## TK (Mar 14, 2014)

How does one have a counterclockwise?


----------



## Mastermind (Mar 14, 2014)

I got a CCW for you bud.


----------



## fastLeo151 (Mar 14, 2014)

Mastermind said:


> I got a CCW for you bud.


How's muh fave monkey buddy doing today?


----------



## Mastermind (Mar 14, 2014)

I'm good. 

Fixin to dive back in on this Dolmar.


----------



## fordf150 (Mar 14, 2014)

opcorn:


----------



## Mastermind (Mar 14, 2014)

I'm sorta slow......but I do real crappy work.


----------



## Duane(Pa) (Mar 14, 2014)

Mastermind said:


> I'm sorta slow......but I do real crappy work.


The beatings will continue until morale improves.....


----------



## fastLeo151 (Mar 14, 2014)

Mastermind said:


> I'm sorta slow......but I do real crappy work.



I know you would rather be porting my purty 064


----------



## fordf150 (Mar 14, 2014)

fastLeo151 said:


> I know you would rather be porting my purty 064


Your nuts! leave that saw alone


----------



## Mastermind (Mar 14, 2014)

Andy is right......I'd rather do a MS660/066/064 than any other saw. 

I just finished a MS650 that went from boring to bad MFer....


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## Mastermind (Mar 14, 2014)

Pics? 

Stock compression.





I used to cut squish by hand.....I had to use that method here. 





Just taking out the lip around the out side in order to tighten the squish up a bit. 









Now to take a little off the base.


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## Mastermind (Mar 14, 2014)

Grindin.....

Rough in.













Finished.


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## Mastermind (Mar 14, 2014)

After port work and machining.

Squish: .019
Ex: 105
Tr: 124
In: 77


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## 7sleeper (Mar 14, 2014)

I wanted to wright something sensible but at the moment....













7


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## wcorey (Mar 14, 2014)

> Just taking out the lip around the out side in order to tighten the squish up a bit.



What's the purpose of that lip? 
I see it on more cylinders than not...


----------



## RedFir Down (Mar 14, 2014)

Hey Randy as always very nice work!! 
The first picture in the second set... is that a long sheet rock screw brazed to the end of that screw driver?


----------



## jimmycrackcorn (Mar 14, 2014)

RedFir Down said:


> Hey Randy as always very nice work!!
> The first picture in the second set... is that a long sheet rock screw brazed to the end of that screw driver?



Haha.. You like that? I noticed that a few threads ago.. Pretty good improvising to get limiter caps out easier. Guy should patent it.


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## fastLeo151 (Mar 14, 2014)

Randy your finished work is very nice


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## Mastermind (Mar 14, 2014)

wcorey said:


> What's the purpose of that lip?
> I see it on more cylinders than not...



It may be a result of the plating process, or it could serve to keep folks from over tightening the squish.



RedFir Down said:


> Hey Randy as always very nice work!!
> The first picture in the second set... is that a long sheet rock screw brazed to the end of that screw driver?





jimmycrackcorn said:


> Haha.. You like that? I noticed that a few threads ago.. Pretty good improvising to get limiter caps out easier. Guy should patent it.



Glad to see y'all paying attention.


----------



## Mastermind (Mar 14, 2014)

fastLeo151 said:


> Randy your finished work is very nice



I do try.


----------



## funky sawman (Mar 14, 2014)

dont let the epa see that tool, they might put it in the same class as belt fed full automatic firearms


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## Treespotter (Mar 15, 2014)

Randy, I have one question and maybe you have the tools to check it. 
The air inlet under the air filter cover is a tiny opening coming from the flywheel. 
Is the flywheel able to over pressurize the air filter compartment? Or is the intake on the flywheel side only able to reject debris. 

Wolter


----------



## sachsmo (Mar 15, 2014)

SawTroll said:


> Definately not pretty - but that isn't what really counts anyway!
> 
> On the heavy side for a 60cc saw, and an inboard clutch, aren't good signs regarding the handling though.
> 
> ...




When this saw first hit the shelves I pointed out at the 'other site' Dolmar has been known to use the same basic 'chassis' for saws of different dispacement. (6400/7300/7900)

That 6100 has plenty of stroke to get it to the 75cc range.

I don't think it would be a bit "porky" at 75ccs eh?

Good work and pics as always there Randy.


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## Mastermind (Mar 15, 2014)

Treespotter said:


> Randy, I have one question and maybe you have the tools to check it.
> The air inlet under the air filter cover is a tiny opening coming from the flywheel.
> Is the flywheel able to over pressurize the air filter compartment? Or is the intake on the flywheel side only able to reject debris.
> 
> Wolter



I'm not sure, and honestly haven't given it too much thought. It does seem to have the ability to keep the air filter nice and clean, but I can't say if over-pressurization was on the minds of the designers.


----------



## Treespotter (Mar 15, 2014)

Probably not. 

Wolter


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## 7sleeper (Mar 15, 2014)

Why not? Would be a rather simple way to increase air speed to eliminate even more "dirt". 

7


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## Mastermind (Mar 15, 2014)

Video is uploading. Port work was good for about a 25% increase.


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## 7sleeper (Mar 15, 2014)

Why does this uploading take so long....








7


----------



## Mastermind (Mar 15, 2014)




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## 7sleeper (Mar 15, 2014)

Very nice!!!






You intend to do a little more majic?

7


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## Mastermind (Mar 15, 2014)

I just ran a ported 562XP with the same chain......it was less than a second faster. That's not bad considering that this is my first attempt with the Dolly.


----------



## fastLeo151 (Mar 15, 2014)

Mastermind said:


> I just ran a ported 562XP with the same chain......it was less than a second faster. That's not bad considering that this is my first attempt with the Dolly.


 
In my opinion that's saying something considering its a little over 500.00 saw


----------



## RedFir Down (Mar 15, 2014)

Mastermind said:


> I just ran a ported 562XP with the same chain......it was less than a second faster. That's not bad considering that this is my first attempt with the Dolly.


Randy I have a feeling you are going to get ambushed with 6100's now!!


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## Mastermind (Mar 15, 2014)




----------



## RedneckChainsawRepair (Mar 15, 2014)

Mastermind said:


> I just ran a ported 562XP with the same chain......it was less than a second faster. That's not bad considering that this is my first attempt with the Dolly.



Tell me about the felt torque in the cut compared? Pushing etc


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## 7sleeper (Mar 15, 2014)

Mastermind said:


> I just ran a ported 562XP with the same chain......it was less than a second faster. That's not bad considering that this is my first attempt with the Dolly.


One has to wonder know, where is the Autotune majic? You know, adjusting the settings during the cut... Kind of reminds one of the test video of 166 of the untuned saws(although the 6100 was brand new)....

Thanks for the honest update!

7

edit: why is your bike burning?


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## Mastermind (Mar 15, 2014)

The 6100 feels slower, but has a butt load of torque. I probably ended up pushing too hard on the 562 after just running the Dolly. With a lighter touch the 562 would have been faster yet.


----------



## Duane(Pa) (Mar 15, 2014)

7sleeper said:


> One has to wonder
> 
> 
> 
> ...



Down on Rocky Top they make Banana flavored Corn Syrup (wood fired) You know...


----------



## fordf150 (Mar 15, 2014)

looks good. The way that runs I'm sure your going to get a second chance at one soon. When is it that you are going to start taking more work again?


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## Mastermind (Mar 15, 2014)

Sometime in mid to late April.


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## fordf150 (Mar 15, 2014)

Let me know when for sure and another 6100 will be sent your way providing I can keep them on the shelf. At the moment they are proving to be a bit difficult to keep in stock


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## Mastermind (Mar 15, 2014)

If you don't mind me hanging onto this one a few more days, I'd like to try a few more things.


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## fordf150 (Mar 15, 2014)

Keep it as long as You want. I should have another order coming in next week or so if you want another one


----------



## Como (Mar 15, 2014)

You could spread the love around...


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## trappermike (Mar 16, 2014)

Some of the Suzuki MX models of the late 70's had crankcase reeds and piston port induction together,but I can't remember the Trade name of the system,I had a new RM370 with it.


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## Deleted member 83629 (Mar 16, 2014)

Save you're self the trouble and send me the dolmar and i will send you a nice poulan wildthing


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## sachsmo (Mar 16, 2014)

Mastermind said:


> The 6100 feels slower, but has a butt load of torque. I probably ended up pushing too hard on the 562 after just running the Dolly. With a lighter touch the 562 would have been faster yet.


 Always best to coddle the brand loyalists that butter your bread eh?

Just kiddin', you hang it out there for all to see.

Kudos on your first try, perhaps that stuff between your ears will come up with sumthin' 'mobetter' on your next tries.


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## bryanr2 (Mar 16, 2014)

the 6100 is a viable option to the 562 at a significant cost savings and for those that dont like bologna. 1 second behind and it is his first attempt..... Id say we have a winner.


----------



## bryanr2 (Mar 16, 2014)

not to mention- the 6100 is a better lookin saw than the 6400 egg.


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## Mastermind (Mar 16, 2014)

Steven, are you considering one of these?


----------



## bryanr2 (Mar 16, 2014)

What I like about the 6100 is that it reminds me of the classic Sachs Dolmar look- particularly the top cover and filter area. For a visual comparison, look at my 120si......

The goofy look of the 562 is a visual negative- it reminds me of a hightop sneaker (as lamented by others in the orig Mastermind meets the 562 thread). If one opts to spend more on the 562 for the 1 sec difference- def the 2260 is the better lookin saw.


----------



## bryanr2 (Mar 16, 2014)

Mastermind said:


> Steven, are you considering one of these?



I can neither confirm nor deny.


----------



## Mastermind (Mar 16, 2014)

The 562 and the 2260 are both mud ugly to me.


----------



## KenJax Tree (Mar 16, 2014)

It ain't no fashion show in the woods boys.


Sent from my iPhone using Tapatalk


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## bryanr2 (Mar 16, 2014)

I agree. It was a major factor in sending my 562xp down the road. I much prefer the "classic" saw look. I like a fast zippy limber, but when I get into larger cuts- I prefer torque over chain speed. Chain speed is going to fade in a big cut to a degree. On the other hand, torque is what drives the chain. I like my saws to run like my diesel trucks- butt loads of torque and pulling might. No they wont beat a Corvette off the line, but yes they will pull a house off it's foundation.


----------



## MRCo. (Mar 16, 2014)

bryanr2 said:


> I agree. It was a major factor in sending my 562xp down the road. I much prefer the "classic" saw look. I like a fast zippy limber, but when I get into larger cuts- I prefer torque over chain speed. Chain speed is going to fade in a big cut to a degree. On the other hand, torque is what drives the chain. I like my saws to run like my diesel trucks- butt loads of torque and pulling might. No they wont beat a Corvette off the line, but yes they will pull a house off it's foundation.


Yessir, you have hit the nail on the head.

F150, I'm constantly running out of them too! As soon as one guy buys one his neighbor turns up to shop his old saw in for one after seeing it in action!


----------



## procarbine2k1 (Mar 16, 2014)

bryanr2 said:


> the 6100 is a viable option to the 562 at a significant cost savings and for those that dont like bologna. 1 second behind and it is his first attempt..... Id say we have a winner.



If you buy a 6100 in lieu of the 562XP, you might not have to eat bologna either. Could probably opt for the 2.99 lb ham instead haha. Looks like a winner to me too


----------



## RedneckChainsawRepair (Mar 16, 2014)

bryanr2 said:


> I agree. It was a major factor in sending my 562xp down the road. I much prefer the "classic" saw look. I like a fast zippy limber, but when I get into larger cuts- I prefer torque over chain speed. Chain speed is going to fade in a big cut to a degree. On the other hand, torque is what drives the chain. I like my saws to run like my diesel trucks- butt loads of torque and pulling might. No they wont beat a Corvette off the line, but yes they will pull a house off it's foundation.




Now you know why I ask about torque earlier. Cookie cutting for times is fine for gtg's (been there done that). But when it comes time for real cutting give me torque.

Most impressive 60cc saw I have ran to date for torque was a 6000i.


----------



## Terry Syd (Mar 16, 2014)

What size carburettor does this saw have?

If you take a shot of the reed block with the reeds off, maybe the inside edges of the block under the reeds could be trimmed to give more area under the reeds. Not only will it increase the area, but also the response of the reeds (pressure differential spread over a larger area).

I notice the reed tips are flush on the surface of the block. If the reeds have a slight curvature (many do) you may be able to flip the reeds over so that the incoming air has less resistance to flow. If a reed has a slight gap under it on the block its not a biggie, the pressure differential will quickly close it so it doesn't leak - even at idle on a full reed engine.


----------



## bryanr2 (Mar 16, 2014)

speed vs torque reminds me of Chad Brocks song "Lightening does the Work" 
Turn it Up Loud Boys!


----------



## Deleted member 83629 (Mar 16, 2014)

i think my saws fall into that category of low speed moderate torque which is fine with me i just need a saw that will hold in the cut.
i ran a old torque monster years ago and it was awesome yes it was slow but it was gear drive and the torque the engine produced made up for the lose of speed
homelite super wiz 80.


----------



## bryanr2 (Mar 16, 2014)

Where does the Echo 600p or 620p fit into the mix with the 6100?


----------



## fastLeo151 (Mar 16, 2014)

Imo the echo saws mentioned are not anywhere the same build quality.


----------



## Mastermind (Mar 16, 2014)

I like the 600P quite a lot myself. Like Andy has said though, the Dolmar is a well built machine.


----------



## Terry Syd (Mar 16, 2014)

I couldn't find the size of the carburettor, but I did find that the USA model has a different High speed needle - http://download.dolmar.com/manuals/23803.pdf


----------



## Mastermind (Mar 16, 2014)

Terry, I'll have to get into it tomorrow to see.


----------



## Terry Syd (Mar 16, 2014)

The reason I'm wondering is I believe the 562 had a 12.5mm carb. Maybe the Dolmar carb is bigger (or smaller). Maybe the relative carb sizes might give an insight into how effective the different strato systems work. That information might then lead to a suggestion on modding.

It appears that the previous Suzuki piston port/reed system and the Dolmar system may have the same advantage, a stronger mid-range/ torque. I wonder if there are any old articles around about modding the Suzuki system.

EDIT: Found one by a former wrench for an Australian team - "We had all the nice stuff like Factory Magnesium Hubs and Fox Airshocks, Engine wise one of the tricks that works with Case Reed Suzuki engines is to double up on the reed petals and in so doing retard the reed timing and then Port the Piston Port intake area for more port timing, Believe it or not that made a nice boost to Torque."


----------



## Mastermind (Mar 16, 2014)

The dolmar carb is much larger.


----------



## bryanr2 (Mar 16, 2014)

How do you think that 6100 would fair against my 359 and 262xp?


----------



## Mastermind (Mar 16, 2014)

About even.


----------



## fordf150 (Mar 16, 2014)

bryanr2 said:


> Where does the Echo 600p or 620p fit into the mix with the 6100?


I really like the 620. They run good and are a nice saw for the money when compared to the other 60cc saws out there. Dolmar seems to have better build quality and better a/v. I Do wish the dolmar had some of the features that the echo has but at over a $100 cheaper I can't complain


----------



## bryanr2 (Mar 16, 2014)

Mastermind said:


> Steven, are you considering one of these?



I'll have to try one of these out, but in a few months. I spent a little over $2k in the last month on saws and it's only March. Gotta save some for later in the year or I will have a really long dry spell of no new toys. That said... I bought me a new 241cm from Jeff which means Im only missing 2 mtron saws- 441cm, and 661cm. I have no interest in the 362cm. When I secure those two Im walking away from saws forever.


----------



## jimmycrackcorn (Mar 17, 2014)

bryanr2 said:


> When I secure those two Im walking away from saws forever.



Haha.... "Just two more." says the cad addict. I think they have programs for that.. Check with your local obumma care rep, it might be covered.


----------



## bryanr2 (Mar 17, 2014)

I purchased private insurance so I dont have to fool with that "fools" solution.


----------



## Deleted member 83629 (Mar 17, 2014)

no i got obamacare and i see nothing under any form that mention CAD now back to dolmar's and other things.


----------



## LegDeLimber (Mar 17, 2014)

Terry Syd said:


> The reason I'm wondering is I believe the 562 had a 12.5mm carb. Maybe the Dolmar carb is bigger (or smaller). Maybe the relative carb sizes might give an insight into how effective the different strato systems work. That information might then lead to a suggestion on modding.
> 
> It appears that the previous Suzuki piston port/reed system and the Dolmar system may have the same advantage, a stronger mid-range/ torque. I wonder if there are any old articles around about modding the Suzuki system.
> 
> ...


----------



## Terry Syd (Mar 17, 2014)

Yamaha's 'Torque Induction' was the boost bottle on the intake. It changed the resonance in the intake tract and gave a nice bit of torque down lower in the band. The Suzuki system was referred to as a 'Power Reed'.

That reference I found to modifying the system on the Suzuki talked about increasing the intake duration and doubling up on the reeds. Allegedly this doubling up was to "retard the reed timing". I figure the wrench just made that up because it sounded plausible, not that it was accurate.

Reeds can be tricky things, the flow characteristics on various reed constructions and thickness varies all over the place. Generally, a thicker reed flows better at high speed and thinner at low speed. Thus, you see something like the Boysen reeds where a thick reed with windows has a light reed on top of it. Essentially, they are trying to get the benefits of both types of reeds.

I figure the doubling up may have dampened some flutter at a certain rpm which improved the power characteristics.


----------



## LegDeLimber (Mar 17, 2014)

My stuff then was all early to mid 70's vintage. Never got to mess with the boost bottles (puberty sorta drew me aside by then)
the yamahas metal reeds would hum if you eased the engine over slowly.
Can't personally recall hearing any of the fiberglass one on other brands doing it.

I remember the magazine articals about the layered or tapered reeds.
aside from restriction and flow rates, the most commonly mentioned theory 
about the taper was to regard it like a super long triangle and thus having no inherent resonant frequency.
Think like a short fishing rod or some old type car aerials.
and if you want some reeds, here's a few for ya.(PB-500 Echo) 

the twin petal feeds the crankcase from the carb and the single petals on the plumbing are the transfer caps and feed from the strato valve.


----------



## Treespotter (Mar 19, 2014)

Randy, I asked you about the air 'pressure' under the air filter cover a couple of days ago. I think I found the answer! 
I drilled a couple of holes in the cover right in front of the rear handle bar. 
It's an overstatement to say my hand froze off, but there was quite a storm flying over my hand. 
Closed the holes again with some duct tape from the inside. 

Wolter


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## nmurph (Mar 19, 2014)

What's the compression post-port? It was pretty strong stock. Was the machining more to get the numbers where you wanted (I know you wanted to raise compression some)?


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## Mastermind (Mar 19, 2014)

Thanks for that info Wolter. That is very interesting. 

Neal it was blowing 195psi before porting. I cut the step out of the squish to get the squish clearance down, and therefore increase velocity. I also wanted to raise the exhaust a little without losing any compression. 

Compression = volumetric efficiency. Dolmar's engineers evidently know that, their engines almost always test at 200psi or so stock.


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## RedneckChainsawRepair (Mar 19, 2014)

Randy after watching all the videos here is what I took from them. 

The 3 stock videos, 6100 run stock with no muffler mod or timing adjustments needed on stock saw. Seems like nothing really gained on just MM and timing adv in videos. 

So either go stock or all the way with ported and other mods done. Is this how you see it?


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## Mastermind (Mar 19, 2014)

That's the way I see it too K.


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## Treespotter (Mar 19, 2014)

I have done a comparison on the test results of the KWF. This is the German test facility that tests forestry equipment. 
Even without techno electronics the Dolly tech people found a way to make it more powerful and still use less fuel than competitors Stihl and Husqy. 


Wolter


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## Terry Syd (Mar 19, 2014)

Dolmar was very clever using the reeds in the strato function and created a strong work saw. The reeds allow the engine to breathe for a longer duration without a problem with blowback. The strong torque at lower revs appears to show two things, first the superior crankcase filling, and secondly, the reeds allow the crankcase to inhale through the reeds below peak delivery ratio so that there is less mixture drawn back down through the transfer ports. 

If someone wanted to raise the point of peak power of the Dolmar, it appears that extra transfer time/area may be the ticket. The reeds would help prevent a serious drop in power below peak torque.

With 25 degrees of blowdown, it is not surprising that a MM mod would have less effect on the power. However, with a muffler mod there is less backpressure to worry about and raising the transfers begins to look like an option. Leave the exhaust stock and see how much extra transfer timing the engine can take before things start going backward. The old trick of nipping the edge off the side of the piston next to the transfers to increase the transfer timing could be a good way to find the 'sweet spot'. When a person has gone too far, then go back to the timing that worked, cut that in the jug and put in a new piston.


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## bryanr2 (Mar 19, 2014)

_these saws for sure are getting my attention now. who is the resident dolmar dealer here?_


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## fastLeo151 (Mar 19, 2014)

There hard to get I think were waiting on 6


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## RedneckChainsawRepair (Mar 19, 2014)

bryanr2 said:


> _these saws for sure are getting my attention now. who is the resident dolmar dealer here?_



Couple dolmar dealers are sponsor here. I like cutting edge username 166. If choosing from NY. Ohio local is around $549 then tax. Can buy online $580 shipped to your door.


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## fordf150 (Mar 19, 2014)

I don't know what luck other dealers are having at getting them but it took me till first of January to get the last of four i ordered at the beginning of October. I ordered 4 more from other warehouses till couldn't find a warehouse with them in stock anymore. Now I am waiting on 6 more that were ordered in first part of January with 2 of those six already paid for and none on the shelf. Same with heated handle 5105's.


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## sugarbush (Mar 19, 2014)

fordf150 said:


> I don't know what luck other dealers are having at getting them but it took me till first of January to get the last of four i ordered at the beginning of October. I ordered 4 more from other warehouses till couldn't find a warehouse with them in stock anymore. Now I am waiting on 6 more that were ordered in first part of January with 2 of those six already paid for and none on the shelf. Same with heated handle 5105's.


you can get 5105 w/heated handles? no problem getting 6100's here in mn.


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## fordf150 (Mar 20, 2014)

Last I checked inventory central power, Atlantic power, and preferred power had zero 5105H, 6400H, 6100 in stock. I have all 3 if them ordered just waiting on them. I just started stocking heated handle 5105H and 6400H but underestimated the demand for them. MN is Magneto power? I am not able to see their inventory


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## Chris-PA (Mar 20, 2014)

Terry Syd said:


> Dolmar was very clever using the reeds in the strato function and created a strong work saw. The reeds allow the engine to breathe for a longer duration without a problem with blowback. The strong torque at lower revs appears to show two things, first the superior crankcase filling, and secondly, the reeds allow the crankcase to inhale through the reeds below peak delivery ratio so that there is less mixture drawn back down through the transfer ports.


Reeds essentially make a variable duration intake port - but that has always been true of reed valve intake systems, yet the industry moved away from them due to other limitations. Here the reeds are on the strato intake, so the air-only inlet has variable timing - the duration of the air-only intake goes up with higher rpm, so the arrival of the fuel mixture will be delayed further at higher rpm (because the air volume in the transfers goes up). The mixture may well be leaned out some too. That is OK to some extent, as it counteracts the normal characteristic of the carb to get richer at higher rpm, but only in small amounts. Hence the small strato air valve and runners, and the conventionally sized carb.

That means this strato system is unable to provide much additional intake volume, unlike a piston-ported strato where the strato intake ports are often larger than the carb - the strato ports become the primary intake to the engine. So this design is just a conventional engine with a short duration intake and a small strato system tacked on. That it makes good torque is no surprise.

I believe Randy ported it by ignoring the strato system, which seems like the only choice. Having done that well the intake porting now flows better, the saws make more power and the strato function is further reduced. But I don't see anything very special in the reed ported strato system.


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## SawTroll (Mar 20, 2014)

Terry Syd said:


> The reason I'm wondering is I believe the 562 had a 12.5mm carb. ........



As far as I know, there are two venturies there?


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## Chris-PA (Mar 20, 2014)

SawTroll said:


> As far as I know, there are two venturies there?


Two throttle plates, but only on carb & one venturi. The strato throttle plate controls just air, no fuel.


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## SawTroll (Mar 20, 2014)

Chris-PA said:


> Two throttle plates, but only on carb & one venturi. *The strato throttle plate controls just air, no fuel*.


Obviously, but that air is part of the total resulting fuel to air mix in the cylinder, as far as I know.


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## Chris-PA (Mar 20, 2014)

SawTroll said:


> Obviously, but that air is part of the total resulting fuel to air mix in the cylinder, as far as I know.


Yes, which is what I was discussing in comment #212 above. 

I think we just hit a language thing - you stated "As far as I know, there are two venturies there?", but the venturi is in the carb, so there is only one venturi but two throttle plates. I know what you meant.


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## sugarbush (Mar 20, 2014)

fordf150 said:


> Last I checked inventory central power, Atlantic power, and preferred power had zero 5105H, 6400H, 6100 in stock. I have all 3 if them ordered just waiting on them. I just started stocking heated handle 5105H and 6400H but underestimated the demand for them. MN is Magneto power? I am not able to see their inventory


surprised 5105h and 6400h would come up as able to order, show discontinued here for quite awhile---- yes magneto power here. there is some old stock 6400h saws in the Wisconsin warehouse.


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## fordf150 (Mar 20, 2014)

sugarbush said:


> surprised 5105h and 6400h would come up as able to order, show discontinued here for quite awhile---- yes magneto power here. there is some old stock 6400h saws in the Wisconsin warehouse.


I can get them.. didn't say it was easy or quick. I can order from magneto but cant check stock and ordering anything from them is expensive. 6100 from them to my shop was $550. Magneto isn't a team player.


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## Terry Syd (Mar 20, 2014)

Chris, there is too much to address in your post. I think this is a case where the proof will be in the pudding. There was one statement "and the conventionally sized carb" which may need to be clarified. I don't remember the size of the carb being stated. A conventional saw of this size would commonly be using a 17mm venturi, but I don't know if that is true in this case.

Randy said it is much bigger than the 562 carb, but didn't quantify it. Perhaps someone with a 6100 could tell us what kind of carb (C3M?) it is running and what size venturi. There is a possibility that a smaller carb (less flow) was used on the saw to bias the system towards more strato air at high rpm. If so, that may open up the possibility of more top end by having a larger carb.


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## Chris-PA (Mar 20, 2014)

Terry Syd said:


> A conventional saw of this size would commonly be using a 17mm venturi, but I don't know if that is true in this case.


Yeah, I'd like to know the carb size too.


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## Tree_Frog (Mar 20, 2014)

My shop ordered my 6100 last Friday. It delivered this Monday.


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## sachsmo (Mar 20, 2014)

Har,

it reminds me of an old 152?


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## fordf150 (Mar 20, 2014)

Tree_Frog said:


> My shop ordered my 6100 last Friday. It delivered this Monday.


Just double checked and my warehouse still doesn't have any in stock.


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## fordf150 (Mar 20, 2014)

Couple other warehouses do have them now so I could order one and have it in a couple days if needed


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## Mastermind (Mar 20, 2014)

Chris-PA said:


> Yeah, I'd like to know the carb size too.



Approximately 16mm


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## sachsmo (Mar 22, 2014)

SawTroll said:


> As far as I know, there are two venturies there?




Two bores, one venturi.

Only need a bore for air since there is no need for a 'low pressure' area to draw the fuel.

And the superior torque is not so much from the design of the strato system.

It is from the stroke, Archimedes said it best eh?


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## SawTroll (Mar 22, 2014)

sachsmo said:


> Two bores, one venturi.
> 
> Only need a bore for air since there is no need for a 'low pressure' area to draw the fuel.



That's just fine with me - it still means that comparing the size of that venturi to carbs that have only one bore/venturi is meaningless.


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## Chris-PA (Mar 22, 2014)

SawTroll said:


> That's just fine with me - it still means that comparing the size of that venturi to carbs that have only one bore/venturi is meaningless.


I understand your point, but it is not quite meaningless. Since the carb is sized like a non-strato saw of this displacement, it is a clue that it is intended to draw air through the carb like a non-strato saw - especially when combined with the small strato throttle plate. Very unlike the Zenoah/Husqvarna piston ported strato system.


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## SawTroll (Mar 22, 2014)

Chris-PA said:


> I understand your point, but it is not quite meaningless. Since the carb is sized like a non-strato saw of this displacement, it is a clue that it is intended to draw air through the carb like a non-strato saw - especially when combined with the small strato throttle plate. Very unlike the Zenoah/Husqvarna piston ported strato system.



It was the 560xp family carbs that we discussed, because of an earlier post in the thread.


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## WKEND LUMBERJAK (May 20, 2014)

Randy did it ever get tested afterporting with a non nodded muffler?


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## Mastermind (May 20, 2014)

I don't know Kenneth. Nate was gonna do some stuff when he got it home. Mower season, and I bet he's swamped at work.


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## fordf150 (May 20, 2014)

We are swamped with stuff right now. I have put a couple tanks through it and it is getting stronger. Really puts a smile on the face of anyone that runs it even when they run the 7900 right before it. I have not come across a nice log to make any videos yet. Biggest stuff we have been cutting is 10 to 14" and my test log at the shop is 30+.


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## Mastermind (May 20, 2014)

I would love to see more of them......evidently they are relatively rare.


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## fordf150 (May 20, 2014)

Rare to get ported but that's the best selling saw I have right now.


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## Mastermind (May 20, 2014)

So supply is keeping up with demand now? 

They are very nice saws at the price.


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## WKEND LUMBERJAK (May 20, 2014)

Mastermind said:


> So supply is keeping up with demand now?
> 
> They are very nice saws at the price.


 I really like mine it cuts well thinking of getting it ported. But really like the decibals of stock.


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## Mastermind (May 20, 2014)

I hear that.......

See what I did there?


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## fordf150 (May 20, 2014)

Mastermind said:


> So supply is keeping up with demand now?
> They are very nice saws at the price.


No problems getting them now. That is finally over with if we can just get the parts situation straightened out.

You may get another one from me. I really like this saw. It is a bit bulky for 60cc but doesn't feel like it when cutting





WKEND LUMBERJAK said:


> I really like mine it cuts well thinking of getting it ported. But really like the decibals of stock.



Randy did a nice job on mine. Single port covered with spark screen which keeps the noise level to just over a stock saw. May be more power with dual port or making the first one larger but I like the noise level it is at. I have intentions of trying out a stock muffler on it as well as enlarging the opening on this muffler just to see what happens but more to do than I have time here lately


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## griz700rocket (Jan 9, 2015)

Just bought a 6100 and want to bump this thread up. Lot's of good info here and wanted to see if anyone has any updates.


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## Mastermind (Jan 9, 2015)

I've done only a few of these saws.......and that's a shame. 

Probably the most overlooked 60cc saw out there.


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## nnero (Jan 9, 2015)

Hope you like it, ours has been great.


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## griz700rocket (Jan 12, 2015)

Got to try out the new 6100 yesterday. Ran like a champ. Power seemed good, starts easily and very impressed with the low fuel consumption.


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## Resaw (Jan 23, 2015)

Has anyone had problems tuning carbs? Not use to strato saw and ours seemed to be running away and I attempted to turn it down and i turned way more than I would usually need to to get any response? Also this thing is cold natured and seems to have an erratic idle on a regular basis was warm. Between cuts while idling it will oscillate up and down just for a second? 
Anybody else see this? 
Also, gas sipper.


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## fordf150 (Jan 23, 2015)

try richening up the low side. had a few that returned to idle kind of slow and were cold natured and that solved my issues


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## Edge & Engine (Jan 23, 2015)

You might want to check the fuel line too, one of the first PS-6100's we sold had a cracked fuel line new out of the box.


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## derailedbus (Apr 8, 2016)

Just picked one up. I blame you all!


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## nstueve (Apr 10, 2016)

derailedbus said:


> Just picked one up. I thank you all!
> View attachment 497031


Fixed that for you...


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## nnero (Apr 10, 2016)

Had a chance to use it yet? Love the pups too!!! We have a pitt/boxer mix.


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## CoreyB (Apr 10, 2016)

derailedbus said:


> Just picked one up. I blame you all!
> View attachment 497031


I have been blamed for a lot worse! I got 6 months on mine and still smile every time I use it. Easily the best saw I have ever ran.


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## derailedbus (Apr 11, 2016)

Just some limbing so far, and just holding it with an evil grin (neighbors are probably frightened), but should get to some big stuff this weekend. Can't wait! Thanks nnero. They're hella ornery, but I love em.


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## derailedbus (Apr 16, 2016)

Got to put it in some pretty big wood today and was incredibly pleased, even though everything I've read shoulda led me to expect it. The only disappointment of the day was my current fitness level. One tree absolutely kicked my ass! Saw never stumbled or bogged down, and I only went through 2 1/2 tanks all day! I do understand why a 2 saw plan is recommended, as limbing with this wore me out a bit, but all in all, I didn't miss my 044 at any point all day.


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## CoreyB (Apr 16, 2016)

derailedbus said:


> Got to put it in some pretty big wood today and was incredibly pleased, even though everything I've read shoulda led me to expect it. The only disappointment of the day was my current fitness level. One tree absolutely kicked my ass! Saw never stumbled or bogged down, and I only went through 2 1/2 tanks all day! I do understand why a 2 saw plan is recommended, as limbing with this wore me out a bit, but all in all, I didn't miss my 044 at any point all day.View attachment 498644


Ya the 6100 is a surprising blast to run. A small limbing saw does pair well. I have a rear handle ms 192 that works well. But there are a lot of great small saws. Dolmar 421 is a very well liked one. Another is would like to try would be an Echo 361p


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## 7sleeper (Apr 17, 2016)

@derailedbus ,

no offense meant, but it looks like you cut through your holding/hindge wood in the cut! This is 'EXTREMLY DANGEROUS! I would advise against doing it. The hinge would look like this when the tree is downed.







You will require some wedges to that the tree does not pinch / jam / back sit onto your saw blade. With the hindge you direct the way it should fall!

Here is a quick overview on how to:
https://www.osha.gov/SLTC/etools/logging/manual/felling.html

here a good video


7


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## derailedbus (Apr 18, 2016)

No offense taken, as I know exactly what you mean. I didn't fell the tree, nor did my saw. I was however, tugging on the rope for a very long time. The tree was dangerously close to my friend's house, and he was comfortable felling it. He insisted on using his MS 290 with a 16" bar and cut the wedge alright but took the backcut from both sides all the way to the wedge and couldn't figure out what was going on. He had put in wedges but those of us on the end of the rope were just wondering why nothing was happening. I took a look at it and it still had a cylinder about 4" round in the middle that he couldn't reach. I shoulda just finished it with my saw but didn't want any responsibility, so we just tied it to his tractor and snapped it off. I just did the majority of the bucking withe my saw, and a little noodling to see what it was like. I've felled a few dozen trees (and all went the way I wanted them to), but still not confident enough near obstacles. I do appreciate the concern, however.


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## Big wood1 (Jan 15, 2019)

Mastermind said:


> About even.


4 years later now do you think the 6100 to be best in class?


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## huskihl (Jan 15, 2019)

Big wood1 said:


> 4 years later now do you think the 6100 to be best in class?


I don't think he frequents this site much anymore. He did a shootout a year ago or so. The 6100, 562, 362, and 357 all came out very similar once ported


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## SmellyPirateHooker (Jan 16, 2019)

Kind of off topic /not off topic but how would the 7910 compare with a 288xp? I'm mean obviously the xp is bigger and I'd expect it to be more powerful but by how much?


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## huskihl (Jan 16, 2019)

SmellyPirateHooker said:


> Kind of off topic /not off topic but how would the 7910 compare with a 288xp? I'm mean obviously the xp is bigger and I'd expect it to be more powerful but by how much?


288 wins on torque or longer bar. I'd say over 24"


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## jimmycrackcorn (Feb 1, 2019)

huskihl said:


> I don't think he frequents this site much anymore. He did a shootout a year ago or so. The 6100, 562, 362, and 357 all came out very similar once ported


Pretty sure you can find him over at ***.. haven't spoken to him in a while though.

Sent from my Pixel 2 XL using Tapatalk


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