661 Muffler mod progression

[redbull660]

Some of this has already been posted...but this is the updated thread.

Been screwing around with various muffler mods on the 661. I'll try and keep this as straight forward as I can... This might take several posts. I'll put the conclusion of each post at the bottom.

First at the Iowa GTG I ran some tests -

(note:with each mod - new chain, bar cleaned, fuel and oil topped off, and reset procedure performed.
Test bar - tsumura 36" 404 tip running new stihl RS chains)

1) stock .625" exit port + stock cover = 31.0 sec big log




2) stock .625" exit port + dp cover I made with .625" port+deflector (pic attached) = 27.8sec ...cut this one a little thin.




found a 2nd log to try out. going to say if you acct for stoppage - 34.8



3) enlarged port on the rear half approx .78" diameter hole + stock cover.

tip was less jumpy dropping in. ~28.2



2nd log again - figuring a short stoppage - im coming up with ~31.4 does seem smoother cutting with this setup...more power.



4) .78" enlarged port on rear half (same as combo #3) + add that dp cover on

someone started cutting on log 2. So I just did two cuts in log 1. Got 29.6 and 29.5 a solid 1.5 sec slower than combo #3.

https://www.youtube.com/watch?v=dUHyjlFRws4

https://www.youtube.com/watch?v=VKkryTHLK_s

my impression was combo # 3 was the most powerful, smoothest (handled the .404 the best) and fastest on avg. especially considering #2 cut 1 was thin and times were pretty close....and log 2 on combo #2 was much slower than log 2 combo #3.

not as scientific as I usually do things but I think it did the job...narrowed things down.

Conclusion so far - .78" enlarged port + stock cover the fastest + most power

 

[redbull660]

The next thing I tried while still at the GTG...

I wanted to try my large port #3 with out a baffle. The closest thing to that was the muffler on Maulhead's ported mastermind 661. The exit port is a bit larger than the .78" enlarged port. It's hogged out top to bottom and back to front approx by deflector ends. But the main thing for me was that the baffle was removed.

Since the muffler was already installed on the saw I decided to just use the saw. Thank you maulhead !

using 30" tsumuara bar + 2 new RS chains... reset performed.

Ported 661 - Mastermind enlarged exit port + baffle removed + stock cover

log 1 - 14.2 sec 13.9 sec



log 2 - 13.0 sec




ported 661 - enlarged exit port .78" + stock cover baffle still in this muffler

log 1 - 13.9 13.8



log 2 - 12.5



Conclusion so far. The baffle removed sounded better but it didn't seem to gain anything even considering the 661 was ported.

So going to stick with the simpler .78 enlarged port + stock cover

 

[redbull660]

Next, a few days after I came home from the iowa gtg

I opened up one of my other 661 mufflers. (see attached pics) I opened it up all the way top to bottom and from back to front approx .95" ...very close to what the MM was. BUT with baffle.


we'll call this "large mod"


large mod vs .78" enlarged.

I ran several tests between these two over a number of days. Reset was performed on both several times etc.


Conclusion - "large mod" was just a little bit ahead of .78" enlarged


At this point my theory was that I probably just needed to open up the .78"enlarged a little bit more, in order to equal the large mod.

Also using them both I felt that the large mod would kinda blip or miss ? during the cut. I talked to my motocross buddy. He basically said the opening was too large and I wasn't maintaining enough constant back pressure? Ok...


SO I opened 78" a little more up to .875" or 7/8ths. see pic 875.

At this point I also had moparway sending his muffler which was really opened up!

 

[redbull660]

Yesterday I tested:

the new .875" (total surface area = .602"sqaured
vs
the enlarged 1.10 tall x .95" wide = 1.05"squared so approx 75% more surface area.
vs
Mopar's mod (see attached pic) = top to bottom 1.10 x back to front 1.10" = 1.20"squared so approx 100% more surface area than the .875"

-------------------------------
bar cleaned, 3 new 404 RS chains, reset performed etc etc etc.

I had to cut up a large cotton wood (approx 4' wide) so I had a lot of time with each mod. I did alot of noodling and really pushed each mod.

Here are the test cuts...

.875 enlarged = 24.6 sec & 21.5 sec



my enlarged port 1.10 x .95" = 26.0 & 22.9 -1.4 sec slower than .875"



Mopar enlarged port 1.10" x 1.10" = 26.7sec & 23.5sec -2.1 sec slower than .875"


Just for a little confirmation. I put the .875 back on with a 24" tsumura 404 + lightly used RS chain on...

22.3 sec ...not same bar length but it is 4 sec faster than the mopar.


Bottom line = I would say a .875" - 1.0" dia. Hole + stock cover is IDEAL. if you make it a square you increase the surface area to much and don't maintain enough back pressure (apparently...according to my friend)

Actually cutting with all 3 - that .875" just really does it. throttle response is way nicer. it doesn't seem dogish at all.

Tests could have been more scientific...ie more cuts. But it didn't need to be. You could tell after using them....so only a few timed cuts were needed to confirm what I was seeing while cutting with them.

 

[Trx250r180]

(I talked to my motocross buddy. He basically said the opening was too large and I wasn't maintaing enough constant back pressure.)

I do not think the saws need the back pressure like the bikes do to run right .

 

[redbull660]

(I talked to my motocross buddy. He basically said the opening was too large and I wasn't maintaing enough constant back pressure.)

I do not think the saws need the back pressure like the bikes do to run right .

Maybe. Maybe not. Maybe it depends on the saw. I don't know. But leaving it in place was faster...at least on the 661.

Then again...maybe the baffle removed with a smaller hole like .875" would be faster yet.

Would be an interesting combo to try! ...can't really think of any other combos.

 

[Trx250r180]

Maybe. Maybe not. Maybe it depends on the saw. I don't know. But leaving it in place was faster...at least on the 661.Then again...maybe the baffle removed with a smaller hole like .875" would be faster yet.
Would be an interesting combo to try! ...can't really think of any other combos.

Could be the m-tronic limitations ,i have never had a m-saw ,i think one of the builders ran a saw with the muffler cover off once to prove they do not need back pressure like a bike does ,the muffler is not an expansion chamber on a saw like on a bike is how it was explained to me .I have noticed better performance by letting them breathe more though.

 

[Adirondackstihl]

Could be the m-tronic limitations ,i have never had a m-saw ,i think one of the builders ran a saw with the muffler cover off once to prove they do not need back pressure like a bike does ,the muffler is not an expansion chamber on a saw like on a bike is how it was explained to me .I have noticed better performance by letting them breathe more though.

I believe that was TreeMonkey and the saw was an 026 IIRC

 

[mdavlee]

I believe that was TreeMonkey and the saw was an 026 IIRC

Timber wolf. 026 is correct for $200 on builders of arboristsite past

 

[funky sawman]

So any difference in bogging with these different mufflers

 

[Moparmyway]

Mine does not bog when the bar is vertical, it just has a very slight hesitation when throttle blipping after the second or third blip when coming off of a cut.

After the muffler mod and air filter was added to mine, it stumbled (4 stroking) in the cut alot, then it cleared up by the end of the second tank.

Also, I am running a MaxFlow air filter with my muffler mod, so the slight bog could be due to the modifications

 

[Flatie]

What happened to the oil thread guys?

 

[Moparmyway]

Everyone finally got tired of reading how bwalker knows everything

 

[blsnelling]

Did you seriously delete the oil thread?

 

[redbull660]

Did you seriously delete the oil thread?

you wanted it locked. Until the tests were done. In 4,000 posts we accomplished nothing!

That thread was a total dis-service to anyone on here trying to LEARN anything from it.

 

[porsche965]

Watched the videos a couple of times. I enjoy listening to the Mtronic system pushing the saw forward, analyzing the wood pull and all the other parameters that it does. My 661 pulls really hard bone stock and with the springs smooth.

Finding more with just a muffler mod is free.

 

[blsnelling]

you wanted it locked. Until the tests were done. In 4,000 posts we accomplished nothing!

That thread was a total dis-service to anyone on here trying to LEARN anything from it.

There's a big difference between locked and deleted. You just took it upon yourself to delete 4000 posts by your fellow members, some of which took time and effort to compose. Some of us gave you the advice you asked for and you never followed through with it. I guess you took your toys and went home huh?

 

[redbull660]

Fellow members don't treat each other like that...an embarrassment to AS.

But, the bottom line, like I already said, it was a total dis-service to anyone on here trying to LEARN anything from it. It served no purpose other than to waste someone's time who would read through it.

Gave me advice and I never followed through...yes I remember all the names you called me. Brad, Have a nice day.

 

[blsnelling]

It's obvious that you're not looking for any help or advice at all. I'm sure glad I didn't port two of your saws for free like you asked me to. That would have been a real waste.

 

[redbull660]

huh? what the hell are you even talking about. Help? Advice? port my saws for free?

help & advice - there was no help or advice. Just an endless amount of insults and name calling.

port my saws for free - yeah you really offered to do that. sure. Even if you did offer, I wouldn't do it, because the tests take to much time, effort, and money. And I'd just get flamed for doing some little this or that not exactly how it should have been done because the results that came out weren't as expected.

I'll do the tests on my 661 and that's it. You think the tests are sooo important. Do em yourself. I don't care. I'm not in the Business of Performance like you. You take the time, find the wood, put forth the effort, buy all the new chains. I know what it takes and it would take a lot ...A LOT to pull it off....more than you probably even realize.

5 or 6 oils , at least 4 saw's per oil. with 3-4 ratios for each oil. That's (depending...) 100+ new chains to make. buy the rolls $$$$$$$$$ make the chains, chains to resell at a loss. Hours making chains, hours prepping/setup of wood, hours upon hours doing the tests, Hours upon hours of uploading. Hours upon hours of editing. So you guys can sit back in your chairs and play 20/20 hindsight and flame, insult, and call me names. No fcking thank you. Did anyone offer to help? NO Did anyone offer to help pay? NO. Did anyone email the companies and ask them what they thought? NO.

Do the tests yourself.

and WHY are you trying to paint yourself as a saint? The thread is gone. The population of AS that knows what happened is pretty low.