Hello. I have a 5 or 6 year old craftsman 50cc saw that has run great over the years, always starts on the second pull. Now it will start the same but after starting it will rev high like I'm pulling the throttle almost wide open though I'm not touching the throttle at all. When I do pull the throttle it dies. If I let it run without the throttle it will just keep going like that, almost can cut through a round with how fast its going. I start it, it revs high, I hit the throttle and it dies. I have to do this maybe 10 or 15 times before it will finally run smooth then if I dont run it for an hour it will act up again. Any help with this out there? Thanks
I’m no mechanic. Not even a Best Western resident. Usually describes an air leak. I wonder if some gunk in the carb could be responsible too. I’d pour some SeaFoam in the tank and see if that helps before I started ripping into it. Probably a long shot but it won’t hurt it any
agree, sounds air leaky swelling closed when something heats up enough to close it. If this has been happening for a while, you might want to check piston to see if it’s started to score yet.
If it is an air leak you wont be doing it any favors by using anything in the gas. It doesn't take long to smear a piston with an air leak.
Thanks guys. After doing some research I concur with the air leak thought. Guess I'll have to look into how to fix it. Is this something I can fix at home?
The easiest and quickest thing to check is if there is an air leak where the carburetor attaches to the piston cylinder. The 2 bolts that secure the carburetor to the piston cylinder may be loose. Depending on the saw, the gasket or the rubber boot between the carb. and cylinder could be torn. On some saws the clamp that secures the carb. boot to the cylinder may be loose or dislodged. I would inspect this area first since any one of these conditions would be an easy fix. A pressure and vacuum test would be best for locating leaks but does require some specialty tools.
