Maintenance & Technical > KX500 Original
Keep fouling plugs
alan:
I would like to hear what doordie thinks about this problem! I wonder if it could be a reed problem? otherwise I would have to go for the CDI?
gowen:
NOw that I think about it, I had a friend that had a little CR80R and was having similer issues. It turned out to be a bent needle jet. Check the condition of your carb's needles/jets.
Remeber your powervalves, they might be stuck causing excessive issues?
KXCam is the man when it comes to these issues. But if it were my bike and the reeds looked fine, I'd start with the obvious. Clean the carb completely. Try leaning the entire circut to see it it helps, then go to compression, then ignition and so on.
KXcam22:
Brett,
It sounds to me like something has changed (failed) on your bike. It would be best not to change jetting or plug heat range - might give you a real surprise later. It is something else. There are a few possibilities to check:
1. I doubt it is the CDI. generally those will cause excessive kickback on starting or low speed mystery seizures. It will not however change your jetting to rich.
2. Cracked/leaking float is possible but you will see lots of unusual overflow from the carb. Also good to check the seat and the needle as leakeage will cause runability problems, but not as super rich as you describe.
3. Cracked reeds: Will make it run like crap but not change jetting to rich.
4. Leaking oil crank seal. Will foul plugs oily black. Bike will run OK but smoke a bit/lot more.
5. Here is what I think it is. Something is wrong with the jet needle in carb. Check the mounting of the needle in the slide. If the needle is not retained (broken clip) it can slide up and make the mid throttle mixture super rich - liker raising your needle a 1/2". Guaranteed to foul plugs. That would create your symptom of running fine (full throttle) on the main jet but dying when you close the throttle to 1/2 -3/4 range (super rich). Bike will also start OK (other than the mostly fouled plug) but start to die as you open the throttle.
Hope this helps. When you find the prob let me know so it will be one more for the memory banks. Cam.
alan:
Thanks Cam! Great INFO! It did sound like cracked reeds to me!
Alan :-D :-D
KXcam22:
Alan,
You still might be right. Enough of a broken reed and the mixture gets sucked back and forth, in and out of the carb and gets progressively richer, the ole "loading up" of the old days pre-reed valve bikes. I forgot about that. Cam.
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