066 no running right - please help

[Dangerous_Dan]

I've got an 066 that starts and runs but will not idle and bogs badly at low rpm. No amount of tuning has corrected the problem. What seems to be an indication to the real problem is that when running with the air filter off a spray of fuel and air is coming out of the carb.
Any ideas on what the problem could be?
I have another 066 I can use for parts. It runs perfect but the engine case is cracked for the oil tank. I can swap whatever turns out to be the problem.
Where do I start?

[Lucky]

Hi Dan.  Swap the carb and see if that helps.  Otherwise you might have an air leak somewhere, and have ot fix it before the saw will run right.   John

[dansaylor]

Try taking the screen out of the muffler my uncles 272 did the same thing and the screen was stoped up....if that works buy a new screen....sounds like more of the problem to me also had a green machine trimmer do the same thing....hope that helps will save some money also to check it first.

[Busy Beaver]

DD.....pull your muffler and check your piston for a heat score. If it has one you could have a stuck ring.
BB

[Sawyerfortyish]

I bought a 064 that spit gas out of the carb and sometimes would preignite when pull starting and just about take your arm out of the socket. I did everything  couldn't get it to idle or set it up to run right. Sent it to a stihl tech and had his head spinning. It took someone to go through the saw piece by piece to figure out what was wrong. At some point in the saws life before I got it someone switched the magnetto. The timming of the saw was wrong. that caused gas to blow out the carb and the preignition. So if this saw is one you don't know the history of and you have a parts saw. Try switching the mag out with the one in the part saw and see if that helps

[Dangerous_Dan]

It's Fixed!
As advised I took the muffler off and the first thing I noticed was the baffle had broken. The broken piece and some little bits were inside the muffler rattling around.  Through the exhaust port I could see the top ring was stuck.  Took the cylinder off and it looks like the piston hit some small metal bits probably from the muffler and pinched the top ring. I swapped out the piston and cylinder from the parts saw and it's running great.
Thanks to some great advice from the FF chainsaw guys,it's back in action!
Thank you,
DD

[Busy Beaver]

DD.....pull your muffler and check your piston for a heat score. If it has one you could have a stuck ring.
BB

Don't mention it! BB