Atc 200 revs up & down by itself

[kormos_93]

My 1982 Atc 200 revs up & down by itself when idling ...What could be causing this? ...( it's really annoying because it's always revving up & is hard on the clutch unless I start it in gear...)


Here's a video of it doing it at the beginning.

http://www.youtube.com/watch?v=3QHlrrm8th0&list=UUVP8wzTgGZsN3R2jFJDSyPQ&index=1&feature=plcp

[WJG1000W]

im thinking air leak or worn rings/piston
to check air leak spray starter fluid around the outside of the carburetor and intake manifold if it revs or sounds differant theres an air leak
to check the rings/piston for where do a compression test should be like 142 - 155 psi or something like that
good idea to post a video that always helps

[muthey]

have you checked the cam chain or valves yet, also go through the carb an pay extra attention to the main needle, to see if it is wore, or jumping up and down.

[kormos_93]

The cam chain is good & The carb is very clean. I have not checked the valves or for an air leak yet. It's probably got an air leak, the sun deteriorated lots of rubber on it. I will have to check the o rings on the intake.

[hoosierlogger]

Carbs will do that when they get wore out. You will drive yourself nuts trying to fix it unless you get a new carb.

[WJG1000W]

if you buy a new carburetor the twenty dollar one from eBay on mine runs great

[hoosierlogger]

if you buy a new carburetor the twenty dollar one from eBay on mine runs great

I have used a couple of those too. If the carb is a close enough match I like to put the genuine factory jets in it. The jets on the china knock offs are hit and miss on being the right size.