I'm a long-time visitor at this site, but newbie member... I am hoping to find some input on my '89 XT600 that I recently bought as-is. It was sitting for several years, and had the usual issues with non-use. I got it running with a new battery and tires, cleaned tank & carbs. 9K orig miles. The problem is that at about half throttle (being ridden; not in Neutral), it hesitates like it's starving for gas. Then if I crank it wide open, it has great power again and is smooth. Let off to half, misses again. Starts on first kick, and idles like a dream. Since hesitation and skipping is only at half throttle and only under load, I am guessing it is in the primary carb. If it were electrical, I would think it would still miss no matter how much throttle. If it were in the secondary carb, I would expect it to be bad only when the secondary is in use (3/4-FULL throttle).
I re-cleaned the main jet and nozzle, but that didn't help. Plenty of gas flow into the bowl, and the spark plug looks good. Anybody seen this problem? I'm not a M/C mechanic, but I am trying to use common sense to troubleshoot this problem. On other threads in this forum, people pointed at the CDI box... I hesitate to blame that though, because again; it instantly goes back to smooth power if I open the throttle wide. The CDI box doesn't sense where the throttle is held, only the engine RPMs.
Thanks for your help and suggestions, Charles
Los Angeles area