idle and pilot adjustment tips

hey can anyone tell me how to get the idle right and the air/fuel mixture right on my kz250. the spark pug is indicating that the fuel mix is way to rich. its a keihin cv36. here a diagram www.kawasaki.com/Parts/PartsDiagram/136031/1983/KZ250-W1

Is this a new problem, that is, has anything been changed that could cause it?

A rich mixture can be caused by several things, like the fuel level being too high in the float bowl, a leaky float, improper jetting. A plug can show a rich reading if the spark is too weak, or if the valve seals are leaking.
Valve lash far out of the specified range can also play havoc with carb adjustments.

What is wrong with the idle?

im almost certain that its the pilot screw that needs to be adjusted, it was running fine before i pulled the carby apart to clean the jets. i removed the pilot screw to see if it was damaged or anything and wasnt sure how far it was supposed to go back in. After running it the spark park was was black on the end so i cleaned it and put it back in and ran it again. Had another look at the spark plug and it was black again. THe idle isnt smooth either

The diagram linked is for the fork. Regardless, for a CV carb 2.5 turns open from lightly seated is typically a good starting point for the pilot screw.

So iv been playing with the pilot screw trying to get it to idle properly, the problem is when I give it a tiny bit of throttle the revs go up to 6k rpm and stay there until you turn the idle screw down. After that the revs go down but then it stalls

Check and be certain the throttle cable isn't binding and holding the slide open. Also might be an air leak. Check the carb boot, if it's cracked air might be leaking in. If the boot isn't screwed securely to the head, air might be leaking in between them. If the carb clamp isn't tightened air might be leaking in at that point. Any air leaks in those places will cause idling problems.

Nevermind... :side:

Its definitely not the throttle cable getting stuck, I was thinking it could possibly be the vacuum getting stuck?

Perhaps be able to find a free FSM download through one of these links.

docs.google.com/document/d/1yZI9yR7otaLb...jm2mH0D2dnRCD-8/edit

motoservicemanual.com/kawasaki-service-repair-manual-download/

Good Fortune!

Ok, I just have to ask. If the engine was running just fine, why did you feel compelled to take the carburetor apart and clean it?

Mainly because the fuel tank was rusted pretty bad, so I wanted to make so the jets weren't blocked before I kept running it

Kz250 enthusiast wrote: Its definitely not the throttle cable getting stuck, I was thinking it could possibly be the vacuum getting stuck?

Did you rule out the sticking vacuum possibility :blink: