Another way to keep that carbon soft is to rev up the engine and flood it out with the choke atthe end of theday. Works good....been doing that for 25 years....never had the 4.2 engine apart for anything. My son-in-law now has the very same chain saw. Cuts like a new one. I can post a photo of a pile of wood he cut that would bury 2 or 3 cars.....cut in about 4 days! Capt,n