Probable causes for hot stalling

[mike_belben]

I have a pair of two strokes that consistently quit as they get heat soaked then work again when they cool off.  One is a husky 142E and the other is a multitek or multiquip(?) 62cc sidewinder concrete saw.. Basically an italian EMAK chainsaw with a vee belt and cutoff arbor.

The 142 runs great except for hot stalling.  The cutoff doesnt want to stay running on the pilot circuit but is fine at WOT.  I figure the carb diaphragm silk has stiffened up or maybe the float tab is off.  

Thoughts?

[pine]

Had an issue with a Stihl 026 many years back that would get that way when hot and it was just the carb adjustment.  Initially I had discarded that as a reason but when I re-tuned the carb,  the problem went away and did not return.

[Gearbox]

I run a big poulon on the processer and I an on the carb every 5 to 10 degrees temp change . Screwdriver is in my pocket all the time I am on the machine .

[mike_belben]

Same here but i cannot dial this out on either unit.  Maybe if i unlimit the carbs but they ran within those boundaries when new so why not now?  I assume there is other cause.

[limbwood]

coil might be bad

[charles mann]

My jonsered was doing the same, got to where i couldnt keep it at mid/high idle going from limb to limb, w/o dying. Replaced entire carb and it seems to be working fine. It'll even sit and idel, while saying, hammering in a wedge, or pick up wedges, which it wouldnt even do new off the shelf. 

[ehp]

most of the new saws are set way to lean from the factory and you cannot turn the jet out because of the limiter on the jet . If saw runs fine until it get heated up then the carb is to lean , as a saw gets hotter is needs more fuel to help with the cooling of the engine . So take a 660 stihl that is used to mill with , in stock form I will set the high speed jet so saw runs at 11,500 rpms at wide open throttle , yes I know that sounds rich but put a tach on that same saw at the end of a long cut milling and it will be over 13,000 rpms , that is from heat in the engine . If you set that saw to factory specs it will die or blow up from heat . Remove limiter and adjust carb to where it runs proper when hot and put limiters back on jets .

[Al_Smith]

Depends on the saw engine design .I know on some of the horizontal cylinder McCullochs the saw dust would build up under the cylinder blocking the air flow across the ignition coil causing it to fail when it got over heated .It would fire up after it cooled off .
Some of the old Homelites with the gas tank out front would boil the gasoline when they got hot probably causing a vapor lock condition .

[Al_Smith]

Somewhat related to heat but not chainsaws .Briggs and Stratton engines using the solid state self advancing magnatron ignitions can go to full advance if they get shut off hot .Even with electric start there is no way to get them started until the coil cools off .With a recoil start it tries to pull your arm out of the socket .With electric start the starter lets the smoke out and if enough of it escapes the starter motor will never work again .