JTTMF wrote: I've just purchased a rebuilt 1983 KZ1000P. It's only done 800 miles since an engine rebuild two years ago and the past year and a half had sat idle. It starts ok, with the odd spit back from the carb and pulls like a bull to 80 mph, but then becomes hesitant and spitty again. Lower to mid revs seem ok. It's got an after market 4-1 pipe and after market cone airfilters.
What's the problem?
Well, I'll say this sounds very familiar to me, including storming up to the peak of 80 mph!
What kind of air filters are you using? If you are trying to use the cheap Emgo "Pod" cone filters on Mikuni CV carbs, well, there's your problem, or at least one of them.
Those filters just plain don't work with Mikuni BS34 CV carbs - period. Somehow, the shape of the filter and mouth disrupts the airflow near the vacuum ports for the needle slides, preventing them from opening properly. Basically, the needle and needle jet circuits are rendered next to inoperative. This creates a very lean condition that gets worse as engine speed increases. If you must run individual filters vs., the stock air box, at least get some proper oval K&N filters, the K&N filter cleaning kit, and follow the K&N instructions. A Stage III Dynojet kit might be a good addition with those filters, too.
As for popping and spitting - sounds like it is running lean at idle also. If the carbs are clean, then check the float levels. Next try 1-1/2 to 2 turns out on the idle mixture screws as a starting point, and see if that helps....
