Muffler Mod - MS291 style
- Thread starter VinceGU05
- Start date
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Stihl working hard
Is it Friday yet
If someone told me that was a factory produced muffler I would believe them outstanding workmanship well done
VinceGU05
PSA vitim.
Thanks SWH.
Planning on running it tomorrow. Will try to do some b4 and after cut times.
Planning on running it tomorrow. Will try to do some b4 and after cut times.
VinceGU05
PSA vitim.
finally done.. roughly a 15% cut speed increase i think we got from it.
stock, sem chisel chain
muffler mod according to my mate had a heap more torque.
my stock 441cm for comparison with full chisel chain
my mate Justin was very happy with the MM and its performance upgrade.
Real nice and not too loud either.
VinceGU05
PSA vitim.
It wasn't the freshest chain but it wasn't that bad either. We checked it b4 starting. our wood is pretty damn hard. !
I was surprised too! Not much louder at all. I guess the louvers keep the noise down rather than just having a big hole.
I was surprised too! Not much louder at all. I guess the louvers keep the noise down rather than just having a big hole.
jdhacker
ArboristSite Operative
I timed it, best I could tell it was 3 seconds slower then the 441. Thats dam good going against a 70cc saw, looks like the mod woke it up. You did a great job, did you have to fatten the carb much. I will be doing mine this weekend.
Tippmann98
ArboristSite Lurker
It's obvious that it was worth doing. Could you share what tuning you did to the saw after the muffler mod?
VinceGU05
PSA vitim.
Think you got the saws mixed up.
First vid stock 291 avg 26 sec
2nd vid is with MM. Avg 23 sec
3rd vid is 441cm avg 14 sec.
Surprisely top end was pretty close. But the bottom end needed fattening up a fair bit.
Don't see it as a tuning 'mod'. It's a simple carb adjustment, which you should be doing often anyway. Learn how to tune a carb on here or youtube and it'll be one of the best 'performance mods' you can do for your saw. Tune often. No 2 running conditions are ever the same.
Just wondering if that muffler has any internal baffling or an open can
VinceGU05
PSA vitim.
Looked like an open can to me.
jdhacker
ArboristSite Operative
Looks kinda like it has a 3/8 or so tube going around the inside of the muffler. It's hard to see, I took mine off and shined a light in the exit port, and you can not see any light on the inside of the muffler.
VinceGU05
PSA vitim.
Those tubes are where the screws go to hold it onto the motor. Other than that I think it's empty in there. No baffle like a 2 piece muffler on a bigger saw.
jdhacker
ArboristSite Operative
No what I am saying, if you hold a pen light to the exhaust port, no light inside the muffler. I''m not talking about the tube where the bolts go. There is some type of tube on the inside I think and its very hard to see.
Jarh73
ArboristSite Member
Thought I better reply to the thread devoted to my new muffler.
Big thanks to Vince for the time and effort of modifying the muffler!
What I wanted to add was my own perspective.
Firstly the Eucalypt we tested on had been dead for over 1 year and I believe it is Manna Gum, a hardwood.
What is hard to get across in the video before muffler modding is how difficult in that size timber to keep the saw running in its sweet spot. Only the slightest extra pressure and it would bog down. Basically a very fine margin between cutting efficiently and bogging down/stalling. I had been using the saw to earlier that day on smaller diameter timber and it was cutting perfectly fine and it didn't do to bad felling the test tree.
The chain may not have been 100% but Vince and I both determined it was more than adequate for back to back testing.
After the MM there was noticeable difference in terms of the amount of pressure required to bog the saw down. The margin between efficient cutting and bogging down was significantly greater. By know means could I bury the saw like Vince was doing but it was cutting much easier. In fact we did a test run before the final muffler mod video so I could get a used to the new found torque and power.
Overall I'm very happy with the outcome and it still appeared to be within the stock tuning range as I have not yet modified the mixture screws so they can turn further.
Will be doing some more cutting over the next few months so will keep you all posted on the long term results of the MM.
The only other outcome from this testing is that maybe I really need a bigger saw for this size timber!
Cheers
Justin
Big thanks to Vince for the time and effort of modifying the muffler!
What I wanted to add was my own perspective.
Firstly the Eucalypt we tested on had been dead for over 1 year and I believe it is Manna Gum, a hardwood.
What is hard to get across in the video before muffler modding is how difficult in that size timber to keep the saw running in its sweet spot. Only the slightest extra pressure and it would bog down. Basically a very fine margin between cutting efficiently and bogging down/stalling. I had been using the saw to earlier that day on smaller diameter timber and it was cutting perfectly fine and it didn't do to bad felling the test tree.
The chain may not have been 100% but Vince and I both determined it was more than adequate for back to back testing.
After the MM there was noticeable difference in terms of the amount of pressure required to bog the saw down. The margin between efficient cutting and bogging down was significantly greater. By know means could I bury the saw like Vince was doing but it was cutting much easier. In fact we did a test run before the final muffler mod video so I could get a used to the new found torque and power.
Overall I'm very happy with the outcome and it still appeared to be within the stock tuning range as I have not yet modified the mixture screws so they can turn further.
Will be doing some more cutting over the next few months so will keep you all posted on the long term results of the MM.
The only other outcome from this testing is that maybe I really need a bigger saw for this size timber!
Cheers
Justin
Jarh73
ArboristSite Member
Quick update; saw has been getting quite a bit of use lately and I have been getting the tuning just right as well perfect idling, hot, cold, warm starting etc.
Running like a dream extremely happy.
The only negative is it uses more fuel but given the extra power it's not really a negative.
Weather permitting I'll be cutting some hard wood around 18 inches in diameter this weekend. Looking forward to it.
Cheers
Justin
Running like a dream extremely happy.
The only negative is it uses more fuel but given the extra power it's not really a negative.
Weather permitting I'll be cutting some hard wood around 18 inches in diameter this weekend. Looking forward to it.
Cheers
Justin
VINIFIREWOOD
I only no what I know
Tho I don't have any experience with the new 291. I have done MM on a couple older 290, 029 series saws. They all responded very well and make an ok saw into a darn good saw. Only down side is more time spent refueling cuz they love the fuel after the mod.
Thumbs up!
Thumbs up!
