Stihl 029 to 039

[Jasonrkba]

I think the kit I used last time had a decomp hole and I plugged it.

 

[HarleyT]

It would suck to have to buy the valve from Stihl, it would cost more than the aftermarket piston/cylinder kit..

 

[Jasonrkba]

True. Those saws are not to hard to crank thankfully.

 

[cookies]

hL supply sells a 2 dollar plug if your ordering parts from them already, think they also sell the husky decomp but I can't remember.
Theres a guy with a listing on this site selling oem ms290 cylinders and a piston that look good, might be a better route.

 

[huskihl]

some things that I think are a must when you do the swap.

new seals like mentioned above

open up the muffler, it's super restrictive and I would image there would be no gain in adding the 390 cylinder without opening it up.

bigger high speed jet. the 290 comes with a .54 and the 390 is .58. I drilled mine out to .64 which is inline with what the brazil only model 390 is.

the bigger jet doesn't hurt its ability to idle or start well either. once warmed up I can start mine with a 1/4 pull of the rope.

The carburetors have adjustable screws on them. Going to a larger jet is equivalent of maybe 1/8–1/4 of a turn out on the H screw. Even going from a stock 029 to a ported 039, there’s never been a reason for me to consider a bigger jet. I just tune them like normal. Faster moving air through the venturi pulls more fuel on its own