hi there i just bought a 94 model cr 125.when riding for the first time it ran perfect until i opened it up over 3/4 throttle in 5th gear, it just bogged then cut out.i pulled in clutch let the revs drop then let clutch out an the engine fired back up an ran fine in lower gears.i had checked air filter,plug and fuel mixture before ride all was ok.oh yeah also noticed bike does not tick over it cuts out and backfires on first 3 to 4 kick overs.any ideas please
thank for the tips guys really helpful cheers. any way after further inspection have found the spark plug not to be the one recomended for the bike however it is compatable. also found reed block assembly is missing the two metal stoppers [unsure of correct terminoligy] could this cause to much air intake at peak rpm or would this effect all gears?
US $4,995.00
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Check compression, could just be low and need new rings.
I agree about checking for possible gunk in the carb, but usually this will cause problems at idle, and not at peak rpm.
Because the bike is hard to start and backfires, that’s more indicative of an electrical problem (if compression is good). Try replacing the spark plug, then the plug cap.
If this doesn’t take care of it, then ride the bike to see if the problem gets worse as the engine gets warmer. If it does, it may be the coil or the CDI.
sounds like a fuel delivery problem. i would check out the float in the carburetor. might have some gunk built up inside it as well