029/290 muff mod - found the sweetspot

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bobd80toy

bobd80toy

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Joined
Mar 4, 2010
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3
Location
ravensdale
i know no one has posted here in a while but i just wanted to say thanks to everyone posting the pics and there in put.

i just picked up a 2006 ms390 for $245 and i didnt even have the saw for an hour and started cuttin into the exhaust! :chainsaw: i was fine with the power it had....but hell, you can never have to much.

i first drilld a 3/8 hole in the indented part and a few 3/16 else where but didnt notice much difference but then i cut away some on the cover plate and noticed a big difference as soon as it started! thanks again!
 
nmurph

nmurph

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Nov 26, 2007
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Somewhere in the space-time continuum
i know no one has posted here in a while but i just wanted to say thanks to everyone posting the pics and there in put.

i just picked up a 2006 ms390 for $245 and i didnt even have the saw for an hour and started cuttin into the exhaust! :chainsaw: i was fine with the power it had....but hell, you can never have to much.

i first drilld a 3/8 hole in the indented part and a few 3/16 else where but didnt notice much difference but then i cut away some on the cover plate and noticed a big difference as soon as it started! thanks again!

congrats......i hope you adjusted the muffler. if not, you will soon be learning how to rebuild a clam-shell.
 
blk90s13

blk90s13

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May 2, 2011
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39
Location
Howell,NJ
Anyone care to walk me through adjusting a carb ? I am wanting to do the muffler mod to the ms290 I picked up yesterday but want to be able and adjust the carb as well


Muffler bearing adjustment ? that is a joke right ? :laugh:
 
Last edited:
cheeves
Joined
Aug 8, 2010
Messages
14,732
Location
Plymouth, Mass. America's Hometown
I proceeded slowly and in multiple steps taking care to test each phase thoroughly with several tanks of gas, kept in good tune, and loaded up in big wood.

First I just reamed out the two existing slots and opened up around the deflector shield exit a good bit, this did very little for performance and the exhaust note hardly changed.

Next I drilled a 5/16" hole in the indented area of the muffler directly inline with the exhaust port which bypasses the internal baffle, surprisingly the increase in throttle response was obvious, running good, sound still well under my Db tolerance.

Today I took a rat file to the 5/16 hole and made it into a slot. Outstanding throttle response, pulls chain alot faster under load, sounds cool with a good "pop-pop" at idle and a tolerable Db at WOT.

I ran two tanks today with a goofy grin on. It sounds and runs so different I decided to pull the plug to make sure I had the carb dialed in right. There's more tan than what this pic shows but it's still whiter than I've ever seen it.

Threw a new NGK in it and opened the H screw just a sniggle, cleaned her up and took pics

IMG_1661.jpg


Here you can kinda see the increased size of the exhaust exit

IMG_1664.jpg


Good-looking 10 year old boat anchor

IMG_1662.jpg
Did very similar work to my brother's 029 and my 310. Like totally different saws now!! IMHO 2 excellent firewood saws!
 
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