661 muffler mod test

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redbull660

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while at the Iowa GTG I tried out some various muffler combos for the 661...

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

So don't just look at the times. Please watch and see if you can tell any differences.

1) stock muffler to establish a base.

big log - 31.0


2) stock rear half + this custom dp cover I made. exit port on it is 5/8ths. .625".

I cut this one a little thin - 27.8 sec



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



3) enlarged port on the rear half + stock cover. opened up port size from .625" to approx .78"

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.



continued to next post...
 
4th) combo = same enlarged port on rear half as #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.






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.

what do u guys think?
 
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
 
Only a couple notes. The stock saw with the stock muffler sounded to be running quite rich. It was hard to tell for sure due to all the background noise. As far as smoothness in the cut, that has nothing to do with your muffler. That's solely a function of the bar tip being in the wood, nothing else.
 
Good stuff. Thanks for sharing this.

I do nothing to the internal baffle. I see no reason to with it being wide open. I simply open up under the stock deflector as much as it covers. Your tests show that to be a plenty, if not ideal. This has become my approach on most saw.

From my testing on the 461 and 660. Removing the baffle completely in a dual port muffler 461 and a dual port muffler 660 caused times to be 1-2 seconds SLOWER on avg in a ~30 second long cut.

That said I don't know what would be the case for a ported 461 or 660.
 
From my testing on the 461 and 660. Removing the baffle completely in a dual port muffler 461 and a dual port muffler 660 caused times to be 1-2 seconds SLOWER on avg in a ~30 second long cut.

That said I don't know what would be the case for a ported 461 or 660.
I don't understand why that would be the case, but it is what it is. I open baffles up, but don't remove them. Thanks for doing the testing for me :)
 
I don't understand why that would be the case, but it is what it is. I open baffles up, but don't remove them. Thanks for doing the testing for me :)

way it was explained to me by my motocross buddy...system has to have back pressure. certain setups of yester years you can almost get away with going with out a muffler lol but not today.

anyway two ways to get it.

have baffle inside - which allows you to open exit ports up more
or remove baffle - so you have to go with smaller exit ports to maintain the pressure.

you won't notice it on the top end. But you will on the idle...it'll be erratic and your fuel mileage will go to sh*t...if you remove baffle that is.

I tested it. He seems to be right.

So... I left the baffles in the 461 and 660 and did triple port exits. The added exits were MINIMAL GAINS but gas milage was preserved but you still got the loud saw effect. heh


I don't have a vid on 660.

here's the 461 vid. was going to do some more with this but never got around to it.

stock setup ash - 38.7 willow (not cottonwood) - 19.2 17.6

stock rear half (with baffle) + dp cover - ash - 36.1 , willow - 16.1 15.7

rear half baffle removed + dp cover - ash 40.3 , willow - 15.7 15.1
so you'd think chain is bad or something in the ash whatever. But it's a carbide chain and the very next cut... (btw the willow was shrinking)

stock rear half (with baffle) + dp cover + 2nd side port (so 3x port)

ash - 35.9sec and wood got bigger! s

 
Good information here Red Bull. Thanks for the time!

I found that the stock 461 liked the stock muffler, not the DP muffler. Now take the 440 or 460 or a 361 stock and they love to have their mufflers modded. What I've found anyway.
 
Good information here Red Bull. Thanks for the time!

I found that the stock 461 liked the stock muffler, not the DP muffler. Now take the 440 or 460 or a 361 stock and they love to have their mufflers modded. What I've found anyway.
I'm very surprised by that. The 461 is super choked up from the factory, just like the 460. I've never tested just a muffler mod, but would expect significant gains as RedBull experienced.
 
Lots of testing was done by you this past weekend! ! :)

I am still in the baffle removed camp, but maybe a stock saw needs that little bit? I know in ported applications, most everyone removes the baffle/birdcage.
 
How did you handle tuning with the various mods? The reason the 40.3 cut was so much longer with the baffle removed, is because the saw was considerably too rich. It 4-stroked in the cut several times. I didn't not notice it being that rich in any of the other cuts, also reflected in the times.

I would readily admit I wasn't very good at tuning at the time. Plus it had the limited coil and limit tabs in place. So for the 461 test above I never touched the H. The H was always all the way rich as far as it would go. The tach would always freak out on me once I hit 13500 on it. Saw was just like that after about tank 6....just amazing. It hauled azz. As for the idle, I'd guess that I had to fatten things up with the baffle removed....and tach worked obviously at low rpm. I always shot for 2700 on idle per madsen's website.

Later on, I removed the limit tab and gained .5 sec on a 18 sec cut by going richer on the H by 1/8 of a turn...after that I was too rich....yeah I went 1/2 a turn richer before I lost significant time though. Never liked the limited coil. Didn't know I could have just switched coils from 660 to 461? oh well.


back to the 661 -


next combo I'd like to try would be the large port (#3) vs an even larger port like moparway has done.

Then i was also considering trying to add a port on the other side of the muffler, but still using the stock cover. Not a lot of room for this. Kinda don't think it'll gain anything, but I still want to know. lol
 
I am still in the baffle removed camp, but maybe a stock saw needs that little bit? I know in ported applications, most everyone removes the baffle/birdcage.
The tests he did on the 661 were on the ported saw. I personally see no reason to remove any baffle, provided it's modded sufficiently to remove any restriction. The 661 baffle more than satisfies that requirement as it comes from the factory. It's wide open. On a saw like the 461, I open it up, perhaps another 1/4". That's just my take on it. YMMV.
 
The tests he did on the 661 were on the ported saw. I personally see no reason to remove any baffle, provided it's modded sufficiently to remove any restriction. The 661 baffle more than satisfies that requirement as it comes from the factory. It's wide open. On a saw like the 461, I open it up, perhaps another 1/4". That's just my take on it. YMMV.

I wouldn't call that a baffle. I was speaking to the 460/461 baffle.

And to comment more on Redbulls post above yours. That saw is limited and 13,500 is the max. Without an unlimited coil and tuning with each mod, I would say all of that is inconclusive.

Your 661 testing is different because of the MT. But the 461 baffle, no baffle is gone.

And Brad, I agree on the stock 661 sounding rich at times. He was making some test cuts when I was headed down for lunch and I even commented to Redbull on how the saw wasn't cleaning up in the cut (was around a 14" willow or cottonwood (soft).
 
I just didn't see much if any more power on the 461 stock with just a DP muffler. More noise was all. Perhaps that limited coil was holding it back.

Seems to me Chadman sometime back found similar conclusions on the dyno if I'm not correct. Don't matter now though after being ported!
Didn't mean to mislead anyone just was my experience. If I remember correctly also my idle was funky with less back pressure also. Steady as a rock now :)
 
The exit port is a bit larger than mine but not that much
4ce7.jpg
 
next combo I'd like to try would be the large port (#3) vs an even larger port like moparway has done.:clap:

Then i was also considering trying to add a port on the other side of the muffler, but still using the stock cover. Not a lot of room for this. Kinda don't think it'll gain anything, but I still want to know. lol

I will also add that I noticed that the 066/660, 046/460, 044/440 run best with the single opening enlarged as big as the deflector will allow as well.

I will modify any one of yours for testing !!!!!
I think its about flow ...........
Triple port and dual port mufflers have different directions they are throwing the exhaust. I believe that the single opening enlarged as big as the deflector would allow helps the saws run best. I could be wrong, but I believe Stihl got the hole in the right spot for best flow ............ they just should have let a 90cc machine breathe out better
 

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It's also about exhausting into the chain speed to carry the exhaust away from the operator. I prefer right hand side ports. Even the DP cover is aimed toward the chain.
 
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