# Mastermind Meets The Dolmar 7910



## Mastermind (Nov 15, 2012)

Here she is.....a brand spanking new 7910. Ain't she a beaut??????

I'm finally getting caught up a little and can get out of the shop early enough to do a thread. 







I've had this saw for a few weeks now. I've done a lot of thinking about it....wondering just how much different it was than the 7900. 

Notice the muffler deflector is different.






I like the brace.....I feel that it was needed on the 7900. 






The decompression valve is in a different place....






The coil is a new and different color.......I've not checked the limit yet. 






The new slab sided light weight piston is on board.


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## bryanr2 (Nov 15, 2012)

hmm. what happened to the Johnsered 2188 thread we were promised in Brad's 390 thread.:msp_sneaky:

And it's about time you did a thread- good reads have been scarce. Been making do on usual AS Drama.


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## Mastermind (Nov 15, 2012)

Everything looks the same here except the decomp....






7900 on the left.......7910 on the right.






Yeah we are porting it so the squish band has been cut. 






A few shots of the stock ports.











Here's where it gets different......


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## Trx250r180 (Nov 15, 2012)

looks like decomps on the angle up on top are getting more common now


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## Majorpayne (Nov 15, 2012)

bryanr2 said:


> hmm. what happened to the Johnsered 2188 thread we were promised in Brad's 390 thread.:msp_sneaky:
> 
> And it's about time you did a thread- good reads have been scarce. Been making do on usual AS Drama.



What happened with the Echo twin you were going to do?


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## Mastermind (Nov 15, 2012)

bryanr2 said:


> hmm. what happened to the Johnsered 2188 thread we were promised in Brad's 390 thread.:msp_sneaky:
> 
> And it's about time you did a thread- good reads have been scarce. Been making do on usual AS Drama.



Sorry.........

Here's a peek at the 390XP.....same saw ya know. 

http://www.arboristsite.com/chainsaw/210537.htm


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## Mastermind (Nov 15, 2012)

Majorpayne said:


> What happened with the Echo twin you were going to do?



I've not got there yet. I was pretty far behind after the KY GTG.


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## barneyrb (Nov 15, 2012)

Mastermind said:


> Here's where it gets different......



Is that molded in or is it an insert? Can't tell from the picture

Edit; I see it molded in from another picture


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## Mastermind (Nov 15, 2012)

The inside of the muffler.......


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## Trx250r180 (Nov 15, 2012)

barneyrb said:


> Is that molded in or is it an insert? Can't tell from the picture
> 
> Edit; I see it molded in from another picture



looks like the sleeves smaller than the casting on the jug


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## Mastermind (Nov 15, 2012)

It's fairly straightforward to dissect the muffler. Just heat and uncrimp the bottom and up the sides a bit.






Then it just slides apart.......with a little bumping and stuff. 






There's nothing to support the flange after removing the crackpipe thingy......so we made a steel support and brazed it to the back half of the shell. 






Then we bolted it to the reshaped exhaust flange and matched it to it.











Now we fix this.....


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## 166 (Nov 15, 2012)

The 7910 is rev limited to 12,800. I have both 7900 & 7910 cylinders here and they look identical except for the deco valve and the exhaust. I have tried using a 7900 muffler on a 7910 and it does run more like a 7900 with that exhaust.

The major changes from the 7900 to 7910 are the cylinder, muffler, crank, & coil.


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## Adirondackstihl (Nov 15, 2012)

I recognize the dealer sticker on that there saw 

opcorn:


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## Plan-b (Nov 15, 2012)

Here's where it gets different......




[/QUOTE]

That looks to be a reverberation ridge.


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## Mastermind (Nov 15, 2012)

In these pics those screws look huge. They don't block the outlet the way they appear. The deflector is 15mm deep and 40mm x 40mm the whole area under it is open and screened. 
















Ported jug........y'all have seen plenty of those.


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## Mastermind (Nov 15, 2012)




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## 166 (Nov 15, 2012)

Adirondackstihl said:


> I recognize the dealer sticker on that there saw
> 
> opcorn:



I recognize the saw with that dealer sticker on that there saw


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## bryanr2 (Nov 15, 2012)

Mastermind said:


> Sorry.........
> 
> Here's a peek at the 390XP.....*same saw ya know.*
> 
> http://www.arboristsite.com/chainsaw/210537.htm



Umm, no it aint.. Nuttin can be compared to a johnny.


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## Mastermind (Nov 15, 2012)

166 said:


> I recognize the saw with that dealer sticker on that there saw



I hope you didn't mind me gutting that muffler. :msp_biggrin:


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## Adirondackstihl (Nov 15, 2012)

Mastermind said:


> I hope you didn't mind me gutting that muffler. :msp_biggrin:



I dont mind a bit.... :msp_thumbup:


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## Mastermind (Nov 15, 2012)

Adirondackstihl said:


> I dont mind a bit.... :msp_thumbup:



Is this one yours?????

I can't keep up.


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## Anthony_Va. (Nov 15, 2012)

Do they make the HD filter setup for these yet? With a flat black cover? I think I like the flat black on tese better than the glossy blk on the 7900. 

Oh yea, I want one too.


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## Stihl-Pioneer (Nov 15, 2012)

Anthony_Va. said:


> Do they make the HD filter setup for these yet? With a flat black cover? I think I like the flat black on tese better than the glossy blk on the 7900.
> 
> Oh yea, I want one too.



I think the flat black looks better also!! :msp_biggrin:


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## SawTroll (Nov 15, 2012)

Mastermind said:


> .....
> There's nothing to support the flange after removing the crackpipe thingy......so we made a steel support and brazed it to the back half of the shell. .....



I believe removing that crackpipe thingy is vital to restore the lost power of the 7910 to start with! :msp_smile:


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## huskydude (Nov 15, 2012)

bryanr2 said:


> hmm. what happened to the Johnsered 2188 thread we were promised in Brad's 390 thread.:msp_sneaky:
> 
> And it's about time you did a thread- good reads have been scarce. Been making do on usual AS Drama.



He promised a 55cp build too and didnt deliver


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## Mastermind (Nov 15, 2012)

166 said:


> The 7910 is rev limited to 12,800. I have both 7900 & 7910 cylinders here and they look identical except for the deco valve and the exhaust. I have tried using a 7900 muffler on a 7910 and it does run more like a 7900 with that exhaust.
> 
> The major changes from the 7900 to 7910 are the cylinder, muffler, crank, & coil.



Thanks for the info. We don't see a bunch of Dolmars here. Most guys have never heard of them....


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## Mastermind (Nov 15, 2012)

huskydude said:


> He promised a 55cp build too and didnt deliver



I sent that cylinder and piston to the owner.......he built the saw. Sorry........I've had a pretty large backlog.


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## rms61moparman (Nov 15, 2012)

21 people on this thread as I type this!!!
Looks like there were several that were "in need of a good read"!!!


Mike


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## Mastermind (Nov 15, 2012)

rms61moparman said:


> 21 people on this thread as I type this!!!
> Looks like there were several that were "in need of a good read"!!!
> 
> 
> Mike



I've only been kicked in the sack three times for threads I didn't have time to do. :bang:


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## Majorpayne (Nov 15, 2012)

rms61moparman said:


> 21 people on this thread as I type this!!!
> Looks like there were several that were "in need of a good read"!!!
> 
> 
> Mike


27 now.


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## huskydude (Nov 15, 2012)

Mastermind said:


> I've only been kicked in the sack three times for threads I didn't have time to do. :bang:



Part of being an AS celebrity


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## Mastermind (Nov 15, 2012)

huskydude said:


> Part of being an AS celebrity



I'm just a barely capable hack with a grinder.


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## Mastermind (Nov 15, 2012)

huskydude said:


> Part of being an AS celebrity



You should send me a 154/254 Meteor piston and your 55 jug......


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## bryanr2 (Nov 15, 2012)

huskydude said:


> He promised a 55cp build too and didnt deliver



Damn Randy, your taking some heat in this one. 

See what happens when we dont get enough biuild threads.


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## SawTroll (Nov 15, 2012)

Mastermind said:


> Thanks for the info. We don't see a bunch of Dolmars here. Most guys have never heard of them....



They can be ordered from Makita here, but no dealer network - it was a little better earlier, but not a lot...


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## SawTroll (Nov 15, 2012)

Majorpayne said:


> 27 now.



The "likes" are about specific posts, and not about the thread as such.....:msp_wink:


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## R2D (Nov 15, 2012)

Boy, this room is packed. How big is your shop Randy? No elbow room at all in here!


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## Mastermind (Nov 15, 2012)

R2D said:


> Boy, this room is packed. How big is your shop Randy? No elbow room at all in here!



My shop is 20' x 10' Mike. I need more room but just for storage....and visitors. :msp_biggrin:


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## Dan_in_WI (Nov 15, 2012)

SawTroll said:


> The "likes" are about specific posts, and not about the thread as such.....:msp_wink:



He is referring to the number of people reading this thread.


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## R2D (Nov 15, 2012)

Mastermind said:


> My shop is 20' x 10' Mike. I need more room but just for storage....and visitors. :msp_biggrin:



AND......how about a live webcam when your "meeting" these saws?


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## Mastermind (Nov 15, 2012)

R2D said:


> AND......how about a live webcam when your "meeting" these saws?



I spent hours on that damn muffler........that would be a boring feed I'm afraid.


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## GBD (Nov 15, 2012)

Mastermind said:


> I'm just a barely capable hack with a grinder.



Could have fooled me :msp_biggrin:


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## Joe Kidd (Nov 15, 2012)

Randy, how did the Jasha 395xp turn out?


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## Mastermind (Nov 15, 2012)

Joe Kidd said:


> Randy, how did the Jasha 395xp turn out?



It's still in the waiting room. I've got a Dolmar 7900, a Echo Twin, a Poulan XXV, and a Jonsered 2171 ahead of it.


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## barneyrb (Nov 15, 2012)

I can see right now this will be another flight without a movie


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## Joe Kidd (Nov 15, 2012)

Mastermind said:


> It's still in the waiting room. I've got a Dolmar 7900, a Echo Twin, a Poulan XXV, and a Jonsered 2171 ahead of it.



gotcha


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## Mastermind (Nov 15, 2012)

barneyrb said:


> I can see right now this will be another flight without a movie



I have a video of it stock in smallish white oak. The video camera is in the shop though. :bang:

Tomorrow we will be running and videoing it after port work.


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## Joe Kidd (Nov 15, 2012)

Have you tried Eutectic 1020 XFC "pink" brazing rod? It's the best I've used for steel and stainless.


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## Mastermind (Nov 15, 2012)

Joe Kidd said:


> Have you tried Eutectic 1020 "pink" brazing rod? It's the best I've used for steel and stainless.



I'll give that a try. I've got a mig but I would rather braze on a muffler.....


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## MechanicMatt (Nov 15, 2012)

Randy why don't you like the Mig with the mufflers? And BTW, looks good as usual.


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## Mastermind (Nov 15, 2012)

MechanicMatt said:


> Randy why don't you like the Mig with the mufflers? And BTW, looks good as usual.



When I was in Tech school the old dude that taught welding insisted that we all start with a 00 torch without filler. I was one of the few that really took to torch welding and have always liked it.


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## bryanr2 (Nov 15, 2012)

Mastermind said:


> It's still in the waiting room. I've got a Dolmar 7900, a Echo Twin, a Poulan XXV, and a *Jonsered 2171* ahead of it.




:msp_wub:

:bang:

:msp_biggrin:

:msp_wink:


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## Warped5 (Nov 15, 2012)

Mastermind said:


> I spent hours on that damn muffler........that would be a boring feed I'm afraid.



I've spent many hours with a muff before ...... and NEVER found it to be boring.


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## bryanr2 (Nov 15, 2012)

Warped5 said:


> I've spent many hours with a _*muff*_ before ...... and NEVER found it to be boring.



Never worked on two just a like either.:taped:


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## 166 (Nov 15, 2012)

Anthony_Va. said:


> Do they make the HD filter setup for these yet? With a flat black cover? I think I like the flat black on tese better than the glossy blk on the 7900.
> 
> Oh yea, I want one too.



A 7910 with the HD filter will run too rich and not come up to RPM. Haven't tried the HD filter on a 7910 with 7900 muffler yet.

Almost everybody likes the black hoods better than the orange hoods. But everybody likes the flat black hoods better yet!


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## Fire8 (Nov 15, 2012)

Mastermind said:


> It's still in the waiting room. I've got a Dolmar 7900, a Echo Twin, a Poulan XXV, and a Jonsered 2171 ahead of it.



I hope 365xt is on the front page or is it on the 2nd page lol


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## Mastermind (Nov 15, 2012)

Warped5 said:


> I've spent many hours with a muff before ...... and NEVER found it to be boring.





Fire8 said:


> I hope 365xt is on the front page or is it on the 2nd page lol



There's a few ahead of it. The line is moving pretty fast though. :msp_wink:


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## Fire8 (Nov 15, 2012)

Mastermind said:


> There's a few ahead of it. The line is moving pretty fast though. :msp_wink:



Is it a low top or high topper just wondering


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## Mastermind (Nov 15, 2012)

Fire8 said:


> Is it a low top or high topper just wondering



Low top. I like them better myself. 

The high top looks a hell of a lot bigger.


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## Tree Sling'r (Nov 15, 2012)

Mastermind said:


> Thanks for the info. We don't see a bunch of Dolmars here. Most guys have never heard of them....



Same here, we call our piggy back gas/oil jugs Dolmar's, not sure why, haha. Very nice job my friend.


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## Fire8 (Nov 15, 2012)

Mastermind said:


> Low top. I like them better myself.
> 
> The high top looks a hell of a lot bigger.



That's cool I just know by the time it gets to okla it be FAST and LOUD


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## Mastermind (Nov 15, 2012)

Fire8 said:


> That's cool I just know by the time it gets to okla it be FAST and LOUD



I never rush on building a saw.......that makes me slow........but my work is crappy so it's OK. :msp_biggrin:


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## SawTroll (Nov 15, 2012)

166 said:


> A 7910 with the HD filter will run too rich and not come up to RPM. Haven't tried the HD filter on a 7910 with 7900 muffler yet.
> 
> .......



That sounds like the HD setup flows less air than the standard one - but can't you just lean out the H setting of the carb a little?


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## 166 (Nov 15, 2012)

SawTroll said:


> That sounds like the HD setup flows less air than the standard one - but can't you just lean out the H setting of the carb a little?



I believe it has more to do with the carb intake elbow than the filter. Would not open up with the filter off no matter where the carb was adjusted. Only tried it on one 7910 but after switching back to the stock filter it ran fine? I have a 7910 here with a 7900 muffler on it and i'll have to try the filter on that saw and see how it works.


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## Termite (Nov 15, 2012)

Mastermind said:


> I never rush on building a saw.......that makes me slow........but my work is crappy so it's OK. :msp_biggrin:


 Like the boys on Duck Dynasty say , if you don't know what you are doing do it fast.


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## Plan-b (Nov 16, 2012)

Plan-b said:


> Here's where it gets different......



That looks to be a reverberation ridge.[/QUOTE]

I am going to correct myself upon thinking about this... 

It's called a reversion dam

It's to prevent re-entry of the exhaust gas.

You keeping it?


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## parrisw (Nov 16, 2012)

Did anyone notice the RPM rating on the flywheel? Says Max 13,500, does that mean the flywheel will explode over that!!! LOL


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## ckelp (Nov 16, 2012)

and that's why we have a test monkey on bored.. so none of us get hurt 

randy, have you tried tig yet?


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## like2surf (Nov 16, 2012)

*slow*



Mastermind said:


> I never rush on building a saw.......that makes me slow........but my work is crappy so it's OK. :msp_biggrin:



Yah! You may not do good work, but your sure slow?


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## Duke Thieroff (Nov 16, 2012)

Mastermind said:


> I never rush on building a saw.......that makes me slow........but my work is crappy so it's OK. :msp_biggrin:



So are your stickers!


Did you get new ones yet?!?!



Just kidding you buddy!

Duke


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## russhd1997 (Nov 16, 2012)

rms61moparman said:


> 21 people on this thread as I type this!!!
> Looks like there were several that were "in need of a good read"!!!
> 
> 
> Mike





Majorpayne said:


> 27 now.



Don't know if it's members looking for a Mastermoobs Meets thread or if it's a bunch of Dolmar fans. Could be both! :msp_smile:


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## Mastermind (Nov 16, 2012)

Plan-b said:


> That looks to be a reverberation ridge.
> 
> 
> 
> ...



It's not a reversion dam.......though I've done that style of exhaust. It mates up to this...






And that is now gone so the exhaust port has been reshaped to fit correctly.


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## Mastermind (Nov 16, 2012)

ckelp said:


> and that's why we have a test monkey on bored.. so none of us get hurt
> 
> randy, have you tried tig yet?



Nope. I want a tig welder pretty bad......next up is a mini mill though. I use a BADP (big ass drill press) and a milling table to do light milling with......it's really slow because it's not stable enough to take more than a .020 cut. I've got to get a better setup. 



Duke Thieroff said:


> So are your stickers!
> 
> 
> Did you get new ones yet?!?!
> ...



I like my ####ty stickers. :msp_sad:


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## ancy (Nov 16, 2012)

*Chit 5 pages to go back and read through!*

That's what I get for taking a night with the family!


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## Plan-b (Nov 16, 2012)

Mastermind said:


> It's not a reversion dam.......though I've done that style of exhaust. It mates up to this...
> 
> 
> 
> ...



Yeah, that snout makes it useless. 

I have to say after they revise that muffler and put a cat in it, thats what that it wil probley be. Cheeper and easyer to change tin then castings.

Good Stuff


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## nstueve (Nov 16, 2012)

subscribed 

Although looking through the thread, I don't see why everyone was telling me not to clean up my 7900 transfers... Looks like Randy is opening and cleaning his on the 7910. I'd still like to know when the AM is going to make us unlimited coils for these saws!


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## Mastermind (Nov 16, 2012)

nstueve said:


> subscribed
> 
> Although looking through the thread, I don't see why everyone was telling me not to clean up my 7900 transfers... Looks like Randy is opening and cleaning his on the 7910. I'd still like to know when the AM is going to make us unlimited coils for these saws!



The 7900 can be a tricky saw to port. They have a small crankcase volume in relation to displacement. Raise the transfers too much and they get really peaky in big wood. I open the lowers just enough to unshroud them.....nothing but smoothing with a diamond burr has been done in the tunnels. 

Port timing numbers off the top of my head.....

Ex: 99
Tr: 128
In: 82


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## SawTroll (Nov 16, 2012)

ancy said:


> That's what I get for taking a night with the family!



Well, I'm still on page one - you can change how many posts you have on each page - I mostly use 100..... :msp_wink:


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## SawTroll (Nov 16, 2012)

nstueve said:


> subscribed
> 
> Although looking through the thread, I don't see why everyone was telling me not to clean up my 7900 transfers... Looks like Randy is opening and cleaning his on the 7910. I'd still like to know when the AM is going to make us unlimited coils for these saws!



Don't trust everything you read, not all advice is good advice! :msp_wink:


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## ckelp (Nov 16, 2012)

SawTroll said:


> Don't trust everything you read, not all advice is good advice! :msp_wink:



hell all of my saws run stock coils, the only one i've have problems with is the wildthinggey it's set at 11.5K for some unknown resin maybe there not designed to be returned by an idiot..


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## Adirondackstihl (Nov 16, 2012)

I hope the movie starts soon.......I'm almost outta poopcorn opcorn:


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## struggle (Nov 16, 2012)

Thanks for the tidbit about heating the muffler up to open the halves. I didn't realize this could be done as I just finished up with a MM on my MS261

Carry on with your thread:msp_sneaky:


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## rms61moparman (Nov 16, 2012)

Plan-b said:


> Yeah, that snout makes it useless.
> 
> *I have to say after they revise that muffler and put a cat in it*, thats what that it wil probley be. Cheeper and easyer to change tin then castings.
> 
> Good Stuff





As of now there will be no cat in that muffler.
That is why it is so funky on the inside.


Mike


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## Mastermind (Nov 16, 2012)

This time change and shorter days screws with me.......I realized that I never even started this saw.......and now it's dark. :bang:


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## Mastermind (Nov 16, 2012)

struggle said:


> Thanks for the tidbit about heating the muffler up to open the halves. I didn't realize this could be done as I just finished up with a MM on my MS261
> 
> Carry on with your thread:msp_sneaky:



The MS261 is a tough one. That stainless steel doesn't bend as well.


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## thomas1 (Nov 16, 2012)

Mastermind said:


> This time change and shorter days screws with me.......I realized that I never even started this saw.......and now it's dark. :bang:









Circo® Monkey Night Light : Target

I paypal'd you $11, commence to makin' videos.


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## Ductape (Nov 16, 2012)

mastermind said:


> this time change and shorter days screws with me.......i realized that i never even started this saw.......and now it's dark. :bang:





boooooooo !!!!


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## DB43725 (Nov 16, 2012)

Mastermind said:


> This time change and shorter days screws with me.......I realized that I never even started this saw.......and now it's dark. :bang:



That why they put headlights on your pickup.......


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## bryanr2 (Nov 16, 2012)

Mastermind said:


> This time change and shorter days screws with me.......I realized that I never even started this saw.......and now it's dark. :bang:



I call BS. You have enough vehicles out there that you could light them woods up.

Guys- this is strictly a ploy to make us wait.


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## bryanr2 (Nov 16, 2012)

DB43725 said:


> That why they put headlights on your pickup.......




and you beat me to it!


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## struggle (Nov 16, 2012)

Mastermind said:


> The MS261 is a tough one. That stainless steel doesn't bend as well.



I used a propane torch and it had to get to a glowing temp before it would bend back. It was much tougher getting it to close back up,but it was far better than cutting and hacking the thing all up.

So far I'm happy with the result and it sounds good yet looks completely stock.


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## Warped5 (Nov 16, 2012)

Mastermind said:


> This time change and shorter days screws with me.......I realized that I never even started this saw.......and now it's dark. :bang:




*BALLOON JUICE, I SAY!*​

If ya weren't paying so much attention to this thread when ya shoulda been filming, we'd have a video to comment on by now! 


:bang: :bang: :bang: :bang: :bang:​


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## Anthony_Va. (Nov 16, 2012)

Whats the deal with errbody picking on my homeboy Randy? :msp_angry:

I got ya back buddy. We know you'll have that vid up tomorrow. I don't want to have to turn on you too. :msp_biggrin:


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## bryanr2 (Nov 16, 2012)

Hell, he lays low forever, not offering us any decent threads. Then he comes in here with a strong start last night on this 7910 and I'm thinking "finally- here we go!" Then we get the usual thread banter wind up on page 7 while Im out working today. Come home expecting this things done been packed up and shipped, only to find that we dont have a stock video let alone a ported one.

Foul play I tell ya- foul play!otstir:



You the man bro!

opcorn:


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## Joe Kidd (Nov 16, 2012)

Mastermind said:


> I never rush on building a saw.......that makes me slow........but my work is crappy so it's OK. :msp_biggrin:



Maybe you need a new set of monkey wrenches for Christmas! :msp_biggrin:


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## Mastermind (Nov 16, 2012)

Anthony_Va. said:


> Whats the deal with errbody picking on my homeboy Randy? :msp_angry:
> 
> I got ya back buddy. We know you'll have that vid up tomorrow. I don't want to have to turn on you too. :msp_biggrin:



Thanks for stepping up big guy. These guys are brutal.......I've just finished for the day and this is how it is?!?!

How about a picture of the bench?






Yeah we got saws to port.


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## Fire8 (Nov 16, 2012)

Mastermind said:


> Thanks for stepping up big guy. These guys are brutal.......I've just finished for the day and this is how it is?!?!
> 
> How about a picture of the bench?
> 
> ...



I sure like the looks of that husq behind the 461 I think these go with it

View attachment 262544


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## Joe Kidd (Nov 16, 2012)

Randy do you barter for saw work? I've got plenty of fresh fruit. :msp_wink:


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## Mastermind (Nov 16, 2012)

Fire8 said:


> I sure like the looks of that husq behind the 461 I think these good with it



Your pics brody.



Joe Kidd said:


> Randy do you barter for saw work? I've got plenty of fresh fruit. :msp_wink:



How fresh? What kind? Is it locally grown or imported? Will you deliver? I just farted.


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## jropo (Nov 16, 2012)

It's Friday.
Sometimes a guy just has to kick back and have some pie.


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## Termite (Nov 16, 2012)

This is a tough crowd you are playing to Randy. I wouldn't want to be in your shoes.
Could you just copy any old 7900 you tube video and post that, these guys wouldn't know the difference they just want to be entertained.
Is that my 576AT behind the 461.


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## bryanr2 (Nov 16, 2012)

Termite said:


> This is a tough crowd you are playing to Randy. I wouldn't want to be in your shoes.
> Could you just copy any old 7900 you tube video and post that, these guys wouldn't know the difference they just want to be entertained.
> Is that my 576AT behind the 461.



I have a selfish motive trying to get this 7910 wrapped up. See that 4th saw back in the picture of his bench....... I drove 100 miles to Johnson City to pick it up. Turned around and drove the 100 back to knoxville, thru knoxville, and another 100 miles to ol Randy's house. I have never cut wood with it, never even heard what it sounds like when it sings etc. I would say I miss it, but I havent spent enough time with it to know it. :msp_wink:

Ive got my heart set on running it Christmas Day.


----------



## Fire8 (Nov 16, 2012)

bryanr2 said:


> I have a selfish motive trying to get this 7910 wrapped up. See that 4th saw back in the picture of his bench....... I drove 100 miles to Johnson City to pick it up. Turned around and drove the 100 back to knoxville, thru knoxville, and another 100 miles to ol Randy's house. I have never cut wood with it, never even heard what it sounds like when it sings etc. I would say I miss it, but I havent spent enough time with it to know it. :msp_wink:
> 
> Ive got my heart set on running it Christmas Day.



Hey at lease you got to touch your saw that pic was the first time I've even seen mine :msp_wink:


----------



## Mastermind (Nov 16, 2012)

Termite said:


> This is a tough crowd you are playing to Randy. I wouldn't want to be in your shoes.
> Could you just copy any old 7900 you tube video and post that, these guys wouldn't know the difference they just want to be entertained.
> Is that my 576AT behind the 461.



No that's a 365XT.......your 576 is on the shelf above the bench. 

Good idea on the video..... 



bryanr2 said:


> I have a selfish motive trying to get this 7910 wrapped up. See that 4th saw back in the picture of his bench....... I drove 100 miles to Johnson City to pick it up. Turned around and drove the 100 back to knoxville, thru knoxville, and another 100 miles to ol Randy's house. I have never cut wood with it, never even heard what it sounds like when it sings etc. I would say I miss it, but I havent spent enough time with it to know it. :msp_wink:
> 
> Ive got my heart set on running it Christmas Day.



That pic was taken this morning sometime........since then your 2171 has been torn down and the squish band has been cut......


----------



## bryanr2 (Nov 16, 2012)

Fire8 said:


> Hey at lease you got to touch your saw that pic was the first time I've even seen mine :msp_wink:



I know what your feeling there bro.:msp_thumbup: It will be worth the weight- I guarentee you that. Repeat business says it all- look at my sig.:msp_thumbup:


----------



## Termite (Nov 16, 2012)

"No that's a 365XT.......your 576 is on the shelf above the bench. "

I can't see it. But at least it is on the top shelf where it belongs.


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## Termite (Nov 16, 2012)

I must be the best thread killer on this site. This is the end of this thread,period,the end,adios,goodbye.


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## bryanr2 (Nov 17, 2012)

nah, this thread will blow up tomorrow morning with the videos


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## Officer's Match (Nov 17, 2012)

bryanr2 said:


> nah, this thread will blow up tomorrow morning with the videos



OK, its tomorrow.


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## Jimmy in NC (Nov 17, 2012)

opcorn:


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## deye223 (Nov 17, 2012)

opcorn:


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## thomas1 (Nov 17, 2012)

Officer's Match said:


> OK, its tomorrow.



No, it's definitely today. I checked my calendar.


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## Mastermind (Nov 17, 2012)

bryanr2 said:


> I know what your feeling there bro.:msp_thumbup: It will be worth the weight- I guarentee you that. Repeat business says it all- look at my sig.:msp_thumbup:



I forgive the hateful things you said about me being slow and stuff. :msp_wink:



thomas1 said:


> No, it's definitely today. I checked my calendar.



Yeppers it is today......I'm in the shop......life is good.


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## DB43725 (Nov 17, 2012)

Mastermind said:


> I forgive the hateful things you said about me being slow and stuff. :msp_wink:
> 
> 
> 
> Yeppers it is today......I'm in the shop......life is good.



Are we havin fun yet,,,,,:msp_wink:


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## Mastermind (Nov 17, 2012)

DB43725 said:


> Are we havin fun yet,,,,,:msp_wink:



Oh yeah. A guy from Knoxville just left here with a saw......he was born in the same hospital, in the same month, same year as me. His mother was working in that hospital....as was mine. Small world ain't it? opcorn:


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## Adirondackstihl (Nov 17, 2012)

opcorn:


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## chainsawnut460 (Nov 17, 2012)

Mastermind said:


> Oh yeah. A guy from Knoxville just left here with a saw......he was born in the same hospital, in the same month, same year as me. His mother was working in that hospital....as was mine. Small world ain't it? opcorn:



Was she a CAD infested monkey too?:hmm3grin2orange:


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## Mastermind (Nov 17, 2012)

chainsawnut460 said:


> Was she a CAD infested monkey too?:hmm3grin2orange:



You talkin bout muh mom Jake? :msp_angry:


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## chainsawnut460 (Nov 17, 2012)

Mastermind said:


> You talkin bout muh mom Jake? :msp_angry:



No just wonderin where you got your disease from


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## Officer's Match (Nov 17, 2012)

thomas1 said:


> No, it's definitely today. I checked my calendar.



Dang it, _still_? It's been today for like_ forever_!


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## Currently (Nov 17, 2012)

Were you switched at birth? 

You ever feel like a square peg in a round hole?


opcorn:

:hmm3grin2orange::hmm3grin2orange::hmm3grin2orange::hmm3grin2orange:


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## Trx250r180 (Nov 17, 2012)

did someone say movies ?


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## Officer's Match (Nov 17, 2012)

trx250r180 said:


> did someone say movies ?



Nope, it's still today. :frown:


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## Trx250r180 (Nov 17, 2012)

he must be still having the movie make up put on ,i heard tommy lee jones was going to play mastermind this time .......


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## Officer's Match (Nov 17, 2012)

trx250r180 said:


> he must be still having the movie make up put on ,i heard tommy lee jones was going to play mastermind this time .......



With Don Knott's doing body double for leg shots.




(sorry Randy, these guys are having a bad influence on me)


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## dancan (Nov 17, 2012)

Mastermind said:


> Thanks for stepping up big guy. These guys are brutal.......I've just finished for the day and this is how it is?!?!
> 
> How about a picture of the bench?
> 
> ...



You just need a longer bench .


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## DSS (Nov 17, 2012)

I don't think there is no dang saw. I think he hijacked those pictures from Snelling. 

Little known trivia facts.....

Randy is actually a midget and Thoimas is kinda 'tarded. 









Hurry up FFS.


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## thomas1 (Nov 17, 2012)

DSS said:


> I don't think there is no dang saw. I think he hijacked those pictures from Snelling.
> 
> Little known trivia facts.....
> 
> ...



At least he can spell "I have a potty mouth". :cow:oop:


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## Mastermind (Nov 17, 2012)

Currently said:


> Were you switched at birth?
> 
> *You ever feel like a square peg in a round hole?*
> 
> ...



I do...... :msp_confused:

Video*s* are uploading......

A stock video with a seven pin.

A ported with a *9 pin*.

Stumping with an 8 pin.

Tearing some poplar up with an 8 pin.


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## Mastermind (Nov 17, 2012)

thomas1 said:


> At least he can spell "I have a potty mouth". :cow:oop:



Not really. I just use speelchek.


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## Dan_in_WI (Nov 17, 2012)

thomas1 said:


> At least he can spell "I have a potty mouth". :cow:oop:



But does he know the number for 911?:hmm3grin2orange:


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## Mastermind (Nov 17, 2012)

This is the one that finished first.....

[video=youtube;bb5M5qIdiHo]http://www.youtube.com/watch?v=bb5M5qIdiHo&feature=youtu.be[/video]


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## Fire8 (Nov 17, 2012)

I really like to watch movie but the movie that will win all the awards will be

Staring the 365XT


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## Mastermind (Nov 17, 2012)

Stock......I was intentionally bogging it and stopping the chain. The saw is a fair runner stock....this video makes it look bad. I wanted to see how much torque it has stock.....

[video=youtube;ve1WBr036cI]http://www.youtube.com/watch?v=ve1WBr036cI&feature=youtu.be[/video]


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## Mastermind (Nov 17, 2012)

With a 9 pin rim.....well just because. It has a butt load of power.....

[video=youtube;UzQIVS_FSho]http://www.youtube.com/watch?v=UzQIVS_FSho&feature=youtu.be[/video]


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## Mastermind (Nov 17, 2012)

With an 8 pin.....

[video=youtube;c9xNVda5JRg]http://www.youtube.com/watch?v=c9xNVda5JRg&feature=youtu.be[/video]


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## Mastermind (Nov 17, 2012)

In poplar....

[video=youtube;Xet-Nr352vg]http://www.youtube.com/watch?v=Xet-Nr352vg&feature=youtu.be[/video]


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## DSS (Nov 17, 2012)

thomas1 said:


> At least he can spell "I have a potty mouth". :cow:oop:



Yes he can. And Good For You too Thomas. :msp_thumbsup:


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## thomas1 (Nov 17, 2012)

Mastermind said:


> Not really. I just use speelchek.



I wasn't referring to you, my thin-limbed friend.




DSS said:


> I don't think there is no dang saw. I think he hijacked those pictures from Snelling.
> 
> Little known trivia facts.....
> 
> ...


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## Mastermind (Nov 17, 2012)

thomas1 said:


> I wasn't referring to you, my thin-limbed friend.



OIC....

There are the videos......I'm goin back to work. :msp_thumbup:


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## DSS (Nov 17, 2012)

thomas1 said:


> I wasn't referring to you, my thin-limbed friend.



Get over it. I've called you worser names. 

Saw seems to run OK Randy.


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## thomas1 (Nov 17, 2012)

DSS said:


> Get over it. I've called you worser names.
> 
> Saw seems to run OK Randy.



No worries. I still like you, in an Andy's finger kinda way.


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## Trx250r180 (Nov 17, 2012)

good job sir :msp_thumbup:


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## Warped5 (Nov 17, 2012)

trx250r180 said:


> good job sir :msp_thumbup:




:agree2:


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## thomasjoven (Nov 17, 2012)

Hmmm.... These vids make me wonder if I shoulda bought one of these as my new falling saw instead of a 461.


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## Trx250r180 (Nov 17, 2012)

thomasjoven said:


> Hmmm.... These vids make me wonder if I shoulda bought one of these as my new falling saw instead of a 461.



Im gonna pretend i didnt hear you say that


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## thomasjoven (Nov 17, 2012)

Haha no buyers regret here! just sayin i'd love to run 'em both but money wouldn't allow for that!


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## Rudolf73 (Nov 17, 2012)

thomasjoven said:


> Hmmm.... These vids make me wonder if I shoulda bought one of these as my new falling saw instead of a 461.



Thats not how CAD works... just get both.


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## Mastermind (Nov 17, 2012)

trx250r180 said:


> Im gonna pretend i didnt hear you say that



Have you been running yours much?

I've got another one here now. Just wondering if there's anything we need to know that could have been better? Does it start well, idle well, plenty of torque????? See what I mean?


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## Eccentric (Nov 17, 2012)

Warped5 said:


> :agree2:



Nice avatar pic Ted.:msp_thumbup:


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## Trx250r180 (Nov 17, 2012)

It runs real good randy,starts like a stock saw,idles if o set it down ,dont have to worry about it dieing has more tourqe,than my other saws,i let a couple cutters run it,they want one now,only 3 tanks of fuel through it,so far,


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## Mastermind (Nov 17, 2012)

trx250r180 said:


> It runs real good randy,starts like a stock saw,idles if o set it down ,dont have to worry about it dieing has more tourqe,than my other saws,i let a couple cutters run it,they want one now,only 3 tanks of fuel through it,so far,



In other words.......don't change anything. :msp_thumbup:


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## Rudolf73 (Nov 17, 2012)

Mastermind said:


> In other words.......don't change anything. :msp_thumbup:



Sounds good to me :biggrin:


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## Trx250r180 (Nov 17, 2012)

Is there any way to get 250 psi in there ??


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## Mastermind (Nov 17, 2012)

trx250r180 said:


> Is there any way to get 250 psi in there ??



Yeah.....but that's a tad much in reality. :msp_tongue:


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## Trx250r180 (Nov 17, 2012)

Im waiting for the downpour to qu:biggrinbounce2:it for a while,ill put the 461 and the xpw up against each other in a big log,that xpwyou did cd is a strong fast saw,am curiois how they compare


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## mt.stalker (Nov 18, 2012)

Another excellent build Master. I just can't grasp the Dolmar/AMC Pacer look ........ Fugly .


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## Mastermind (Nov 18, 2012)

mt.stalker said:


> Another excellent build Master. I just can't grasp the Dolmar/AMC Pacer look ........ Fugly .



I'm still experimenting with port timing numbers on the 7900......but I think these may be my favorite so far. 

I like the looks of these things though.


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## Dan_in_WI (Nov 18, 2012)

mt.stalker said:


> Another excellent build Master. I just can't grasp the Dolmar/AMC Pacer look ........ Fugly .



Blaspheme!

(The Fugly part, not the excellent build part.)


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## parrisw (Nov 18, 2012)

Mastermind said:


> I'm still experimenting with port timing numbers on the 7900......but I think these may be my favorite so far.
> 
> I like the looks of these things though.



I must of missed the numbers? Did you post them? I need to hollow out the muffler on mine still.


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## Mastermind (Nov 18, 2012)

parrisw said:


> I must of missed the numbers? Did you post them? I need to hollow out the muffler on mine still.



On this saw.....

Compression 190psi
Squish .022
EX: 102
TR: 128
IN: 84
Ignition timing advanced 6°


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## parrisw (Nov 18, 2012)

Mastermind said:


> On this saw.....
> 
> Compression 190psi
> Squish .022
> ...



Nice, a little less Blowdown then normal? A little more Conservative on the ex?


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## Mastermind (Nov 18, 2012)

parrisw said:


> Nice, a little less Blowdown then normal? A little more Conservative on the ex?



That's a good number on the exhaust for torque IMHO. 

I did a 7900 at the same time with 99, 128, 84 to do some R&D testing. The differences are small enough that most guys would never notice but we will see which is best for a true work saw.


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## parrisw (Nov 18, 2012)

Mastermind said:


> That's a good number on the exhaust for torque IMHO.
> 
> I did a 7900 at the same time with 99, 128, 84 to do some R&D testing. The differences are small enough that most guys would never notice but we will see which is best for a true work saw.



Right. I don't like going above 98 on ex, if you can keep comp up, I'm not afraid to go that high. Most of the huskies I've done are about 100, the last 372 was at 98, but it has big comp, so well see how it does.


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## Wild Knight (Nov 18, 2012)

How much can you really change the shape and timing of the ports if you are rev limited?


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## Mastermind (Nov 18, 2012)

Wild Knight said:


> How much can you really change the shape and timing of the ports if you are rev limited?



It being rev limited has nothing to do with porting the engine for more power and torque. This saw won't be on the limiter in the cut.........unless it's limbing.....and that would be a good thing.


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## Wild Knight (Nov 18, 2012)

Mastermind said:


> It being rev limited has nothing to do with porting the engine for more power and torque. This saw won't be on the limiter in the cut.........unless it's limbing.....and that would be a good thing.



Is there a rule of thumb for what changes in the ports create more torque with a broader power band, rather than creating peak power at max RPM?


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## Mastermind (Nov 18, 2012)

Wild Knight said:


> Is there a rule of thumb for what changes in the ports create more torque with a broader power band, rather than creating peak power at max RPM?



Not any hard and fast rules that I'm aware of, but generally a higher exhaust port raises rpm at the expense of torque. I tend to run a lower exhaust along with more compression for a strong, torquey saw.


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## Mastermind (Nov 22, 2012)

Termite said:


> I must be the best thread killer on this site. This is the end of this thread,period,the end,adios,goodbye.



Your PM box hicky thing is full too. :msp_tongue:


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## Trx250r180 (Nov 22, 2012)

What was he really trying to say ?


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## Mastermind (Nov 22, 2012)

trx250r180 said:


> What was he really trying to say ?



Su caja PM Hicky cosa está llena demasiado


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## Mastermind (Nov 22, 2012)

الشيء الخاص بك PM hicky مربع مليء جدا


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## B Harrison (May 26, 2013)

I really want this done now!

Why do I have to have a baby on the way and an unported 7910 at the same time.


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## Mastermind (May 26, 2013)

B Harrison said:


> I really want this done now!
> 
> Why do I have to have a baby on the way and an unported 7910 at the same time.



I've done two 7910s in the last month......


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## 7sleeper (May 26, 2013)

B Harrison said:


> I really want this done now!
> 
> Why do I have to have a baby on the way and an unported 7910 at the same time.



No sure you have your priorities set correctly.

7


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## bryanr2 (May 26, 2013)

B Harrison said:


> I really want this done now!
> 
> Why do I have to have a baby on the way and an unported 7910 at the same time.



Put "porting 7910" n the baby shower gift registry "as necessary to put food on the table" or "necessary stress relief"


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## tdi-rick (May 26, 2013)

Joe Kidd said:


> Have you tried Eutectic 1020 XFC "pink" brazing rod? It's the best I've used for steel and stainless.





Mastermind said:


> I'll give that a try. I've got a mig but I would rather braze on a muffler.....





Mastermind said:


> When I was in Tech school the old dude that taught welding insisted that we all start with a 00 torch without filler. I was one of the few that really took to torch welding and have always liked it.



Randy, I've had to do a lot of brazing over the years and with SS you need to treat the surface with 'pickling paste' (not sure what you'd call it over there, it's an acid gel) to get rid of the oxides in the stainless and use a high silver content rod, not brass.

I usually use a 45% Ag rod as that's what I have for steel/copper or steel/brass, but a higher silver content will wet out even better.

I absolutely lurve my little Harris 15-3 torch. Can do (almost) TIG quality welds with it. (when not brazing )


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## Mastermind (May 26, 2013)

tdi-rick said:


> Randy, I've had to do a lot of brazing over the years and with SS you need to treat the surface with 'pickling paste' (not sure what you'd call it over there, it's an acid gel) to get rid of the oxides in the stainless and use a high silver content rod, not brass.
> 
> I usually use a 45% Ag rod as that's what I have for steel/copper or steel/brass, but a higher silver content will wet out even better.
> 
> I absolutely lurve my little Harris 15-3 torch. Can do (almost) TIG quality welds with it. (when not brazing )



I just started using silver solder........amazing how little it takes.


----------



## barneyrb (May 26, 2013)

Mastermind said:


> I just started using silver solder........amazing how little it takes.



Will silver solder take the heat generated? I'm asking because I honestly don't know, not trying to be a smart azz........


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## tdi-rick (May 26, 2013)

Mastermind said:


> I just started using silver solder........amazing how little it takes.



It's really easy to overheat and boil the silver, most blokes use too much flame directly on the solder so try and capillary the heat with something like steel that doesn't conduct heat away too quickly and lift the heat away quickly too.
When the heat is right it capillaries and follows the heat beautifully, leaving a really nice fillet, get it wrong and turns ugly really quickly.
Tip selection is important, just like fusion welding.

I've seen some shocking brazed joints by blokes that have been doing it for a long time, wrong tip, wrong heat and just don't care attitude I'd reckon.
I've often had the job of fixing the #### ups.


----------



## Mastermind (May 26, 2013)

barneyrb said:


> Will silver solder take the heat generated? I'm asking because I honestly don't know, not trying to be a smart azz........



Depending on the content it has a melting point between 800 and 1200° F.


----------



## Mastermind (May 26, 2013)

Stolen from Tom Walz......

"Silver Solder Versus Silver Braze

I just got another call from somebody that had a lot of problems with brazing. 

Once we got into it, it became apparent that the problem was that he was trying to use silver braze alloy with a silver solder flux. He wasn't clear on the difference between silver soldering and silver brazing. He went to a welding supply store where the clerk wasn't clear on the difference either and the clerk sold him soldering flux for a brazing application.

Flux does a lot of things but primarily it is an oxygen interceptor. It is designed to keep the materials from oxidizing during brazing. If you get an oxide layer formed the braze alloy and the two parts being brazed will not join together.

Silver solder is a solder which has typically 1% to 3% silver in it and melts around a couple hundred degrees Fahrenheit. Silver braze or silver braze alloy may have 30% and 60% silver and it melts above 1100°F. These are approximations but they serve to illustrate the difference.

Typically brazing takes place above 800°F and soldering takes place below 800° Fahrenheit.

Silver solder flux and silver brazing flux are two very different compounds. Silver solder flux is designed to become active at very low temperatures and to work at very low temperatures. Silver brazing flux becomes active around maybe 500°F or so and stays active up to maybe 1500°F.

If you use silver solder flux for silver brazing then the silver solder flux will be all used up before the metals get anywhere near hot enough. If you use silver brazing flux for silver soldering the metals will be heavily oxidized before the flux even begins to become active.

The term silver soldering is often used to cover all joining using silver of any the amount and thus covers silver brazing as well. I am as guilty of doing this as anyone.

I think it would be for the general good of the industry overall, and certainly the new people, if more care was taken in differentiating between soldering and brazing.

The latest guy to call was a nice young guy and he had messed up $50 worth of parts which was a lot of money to him. I kind of hate to see that happen to anyone."


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## tdi-rick (May 26, 2013)

barneyrb said:


> Will silver solder take the heat generated? I'm asking because I honestly don't know, not trying to be a smart azz........



Melting point is around or above 600*C so I reckon it's pretty safe.

The high silver stuff (>45%) should be good for well over 300*C service and you need at least that high silver content to work and wet out steels, otherwise it won't work.


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## Jon1212 (May 26, 2013)

Mastermind said:


> I just started using silver solder........amazing how little it takes.



The other advantage over welding rods is you never get confused which one is your leg, and which one is the welding rod. If you wore shoes on occasion it could help avoid a serious injury. Just sayin'


----------



## Mastermind (May 26, 2013)

Jon1212 said:


> The other advantage over welding rods is you never get confused which one is your leg, and which one is the welding rod. If you wore shoes on occasion it could help avoid a serious injury. Just sayin'



Muh wife bought me some shoes Thank You Very Much. :msp_mad:


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## Jon1212 (May 26, 2013)

Mastermind said:


> Muh wife bought me some shoes Thank You Very Much. :msp_mad:



Wal Mart branded Crocs don't count. Even if you do fancy the pink ones.


----------



## Mastermind (May 26, 2013)

Jon1212 said:


> Wal Mart branded Crocs don't count. Even if you do fancy the pink ones.



These are Garmont's :msp_sneaky:


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## B Harrison (May 27, 2013)

I get fussed at for reading this stuff, I need to go cut firewood or something.


----------



## shorthunter (Jun 25, 2014)

Mastermind said:


> The inside of the muffler.......



Just curious here, did you measure the exit on the SLR insert? What about the inlet? Muffler canister exit?


----------



## Mastermind (Jun 25, 2014)

Never bothered.....just chunked it.


----------



## shorthunter (Jun 25, 2014)

Well damn. I don't really want to rip mine apart but I am curious about the dimensions.


----------



## VINIFIREWOOD (Jun 28, 2014)

Randy
Between the 7900 and the 7910, which is the better ported saw?


Sent from my iPhone using Tapatalk


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## Mastermind (Jun 28, 2014)

No real difference.


----------



## VINIFIREWOOD (Jun 28, 2014)

I read something about the crank being different in the 7910, do you know what they changed or what is diff?


Sent from my iPhone using Tapatalk


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## Mastermind (Jun 28, 2014)

Not that I see. 

Same crank, piston, etc. 

The jug is different at the exhaust flange....but the timing numbers are the same.


----------



## cgraham1 (Jun 28, 2014)

VINIFIREWOOD said:


> I read something about the crank being different in the 7910, do you know what they changed or what is diff?



http://www.arboristsite.com/community/threads/ps-7900-vs-ps-7910.202467/



cuttinscott said:


> Well the NEW PS-7910 are selling, and anyone that has bought them or tried them has been HAPPY. As far as NET Weight for Power Head Only as comes in the box here are the results...........
> Stock Dry New PS-7900 per our digital UPS Legal scales 14.8 pounds
> Stock Dry New PS-7910 per our digital UPS Legal scales 14.8 pounds
> Hmmmm same weight, brattier exhaust note, NO CAT, Adjustable Carburator, 15% better on fuel, cleaner running to keep the EPA happy whats not to like??
> ...





cuttinscott said:


> The PS-7910 coil is Limited to 12,800 in lew of the 13,500 on the PS-7900 But like I said side by side stock to stock they are VERY CLOSE I need to test with a broken in saw seeing when we tested them it was a year old 7900 vs out of box 7910. _The crank is the same design I believe the timing changed and was told the crank also has been strengthened.._
> Scott


----------



## Mastermind (Jun 28, 2014)

Cool. 

I love to learn new stuffs.


----------



## VINIFIREWOOD (Jun 28, 2014)

cgraham1 said:


> http://www.arboristsite.com/community/threads/ps-7900-vs-ps-7910.202467/



Nice. Knew I had read that somewhere
Thanks


----------

