[instrumentofwar]

My son's KFX 50 has been having a few issues. Hoping someone here can provide me with a bit of insight.

When starting cold I have to pull off the seat and hold my hand over the intake. After she fires up, if I take my hand completely off the engine cuts out. After it's warm I don't need to choke the air-flow, but the engine is very sensitive to the throttle. If you get on it she'll cut out.

I have played with the idle adjustment, but that really hasn't helped much.

Any ideas would be greatly appreciated, thanks much

[mbarryracing]

Was the machine sitting for any length of time with stale fuel in the carb? Sounds most likely that you have some jets that are getting varnished up and restricted, causing a classic lean fuel condition. But also a slight possibility of a vacuum leak in the intake or crankcase...

[instrumentofwar]

mbarryracing, on 19 July 2010 - 07:53 AM, said:

Was the machine sitting for any length of time with stale fuel in the carb? Sounds most likely that you have some jets that are getting varnished up and restricted, causing a classic lean fuel condition. But also a slight possibility of a vacuum leak in the intake or crankcase...

Pull apart for a good GI clean? She has setting for awhile

[mbarryracing]

Yeah, see how bad it is gunked up inside (green cheese, etc). If so, might have to soak the jets in a cleaner solvent to dissolve the varnish since nothing else (short of scrapping it out) will touch it.
If the float bowl is pretty clean then likely just loose sediment that is in the slow jet, then spray carb cleaner followed by compressed air will usually do the job.