FIXED - "Warm" start issues - MS250

[farmguywithasaw]

250s are known for this. I hated mine for the same reasons. I put an aftermarket Chinese carb on it and it is 100% reliable and a great saw now. It is my ATV saw and never fails to start in any condition. I don’t know what in the factory carb causes this, but rebuilding doesn't fix it.

https://www.amazon.com/gp/product/B06XWHHGHH/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

I put an 025 carb on the one I have

 

[Bob Hedgecutter]

Ok well I feel stupid now. I ordered a new coil, went to replace it, and saw the factory coil was caked with oily sawdust. I simply cleaned that off and sanded the flywheel magnents a bit. Put it back together and tried the warm start thing. Worked 5/5 times.

Kind of odd that it didn't have issues starting cold or hot, but there you go.

This is a VERY common issue and you are not alone.
I would hazard a guess that every secondhand saw I pick up that has been previously owned by a non-pro user has the same gunk packing the air ducts and coil pockets. All that gunk prevents the flywheel fan cooling the coil- heat kills spark.
Many saws I find have never had the recoil starter of air deflector plate removed unless something has broken inside- air vents in the cover are packed with crud, air gap between flywheel and crankcase bottom is full of crud, coil pocket full of crud.
I am about to go pick up a saw today from a 1990's vintage manufacture- willing to bet it is the same.