290 to 390 issues

[grizz55chev]

Dont have a tester atm...just by pulling on it seems good but I know thats not exact

Might try putting the timing back where it was, you have to start somewhere. I just finished my third 290 to 390 conversion with a cheap $25 china kit, it runs like a scalded dog with only a muffler mod. Easily cuts anything i put it into, mostly oak in the 18 to 20 inch diameter.

 

[Junkwrencher]

Dont have a tester atm...just by pulling on it seems good but I know thats not exact

A rough test is to pick the saw up by the pull rope. With the pop-up piston the engine should not turn over. With yours being non-compression release was it new old stock or off a used saw? The one I posted the picture of is from 1992.

 

[Junkwrencher]

A rough test is to pick the saw up by the pull rope. With the pop-up piston the engine should not turn over. With yours being non-compression release was it new old stock or off a used saw?

Putting the port modification into the equation, was port timing changed, port width or just an enhancement/polish?

 

[Junkwrencher]

Might try putting the timing back where it was, you have to start somewhere. I just finished my third 290 to 390 conversion with a cheap $25 china kit, it runs like a scalded dog with only a muffler mod. Easily cuts anything i put it into, mostly oak in the 18 to 20 inch diameter.

Might try putting the timing back where it was, you have to start somewhere. I just finished my third 290 to 390 conversion with a cheap $25 china kit, it runs like a scalded dog with only a muffler mod. Easily cuts anything i put it into, mostly oak in the 18 to 20 inch diameter.

The ignition timing would be interesting. The ones I have experience with have the key built into the flywheel right?

 

[Junkwrencher]

The ignition timing would be interesting. The ones I have experience with have the key built into the flywheel right?View attachment 813006

I just bought a flywheel for one not long ago...This one is out of time....

 

[Definitive Dave]

consider installing the OEM heat shield between the muffler and cylinder that only the 039/MS390 has, it is there to keep the larger, hotter-running motor from becoming heat soaked from the muffler side and going lean from that cause