I just bought a used 91 Bayou 300 4x4 and it starts up great and idles fine but when you get above 1/3 throttle it starts missing, stumbling, and running really rough. But on saturday It started doing that so I drained the gas used some carb cleaner through the fuel tank changed the plug and it did it for awhile but then it cleared up again and ran great all day long but now its doing it again. I also took the carb off and removed all the needles and cleaned very good and adjusted the float. I think it may be the cdi or regulator but i was told that if the cdi was bad it would stop working all together. Please Help.

Thanks

Rob Atha
mom2kids76@verizon.net

 

Was there alot of crud in the float bowl? If it doesnt have an inline fuel filter on it, clean the carb again, and put a filter on. If you have a metal tank, it could have rust inside, and this is whats plugging things up, or it could just be acumulated dirt and dust from 13 years of use, that have settled in the gas tank, and as you drive around, this stuff gets stirred up and flows into the carb.
The cdi, on a 1991, wont know or care what throttle position you got, its almost certainly a carb problem.

 

The floats had a light rusty like film on them but nothing really bad. I will take the carb out again and check it for more crud.