I hope somebody can shed some light on this one. About 1 month ago I noticed the machine would miss and seem to lose power, we replaced the air filter and the problem went away. But now it is really bad and fouling the plug with Black carbon and I cannot get any top end at all. I pulled the carb and cleaned all the jets,etc and set the idle and air mixture needles as per manual but that just seemed to make things worse. If I rev it up it just puts out extremely black smoke and backfires alot.

Can anybody shed some light on the black carbon? Could this be ignition timing? I cannot get the rpm's to settle down at 3000 or under.

Help... Hunting starts in two days...aarrghh!! always something to go wrong

 

Pull the speed limeter black wire and if the problem goes away replace the module. If not then the camshaft has worn flat on the exhaust lobe.
The new cam is a lot better with larger and more oil holes and better hardfacing.

 

I am having this same problems... Does anyone have a fix?