Im having hot start problems on my 2000 kawasaki zx7r. It used to be a problem only when I shut off the engine when it was hot enough for the fan to be on. Had to let it sit 10 min or so before it would crank. Its been getting worse, and today it wouldnt start after just a 5 mile ride to the gas station in 65 degree weather. The engine was barely up to operating temp.



The carbs should be at least decently balanced, that was just done this spring. The float bowl plungers and seats are all in good shape(just checked them this weekend), and the idle mixture is a little on the lean side. I havent made any adjustments to the tuning since it was running flawlessly, even hot starting fine a year ago. The plugs only have a few thousand miles on them.



The carbs are Keihin CV's, but Im hoping someone has some good general knowledge of carbs and can get me going in the right direction.

Stuck float?

So, did you get this sorted out?



I just saw the thread due to a spammer giving you a bump. My guess is that it's flooding due to a leaky needle valve, or sunk float. Try shutting off the fuel petcock before you kill the engine and let it burn some of the gas out of the float bowls. See if it starts better. If it does, that's probably the issue.

I did get it sorted, but it just makes me hate carbs even more. I cant believe how damn finicky these carbs are.



There are a series of 5 metering holes drilled into the bore right at the throttle plate that controls the mixture at idle and just off idle. All are fed by the pilot jet, and the first one is further controlled by the idle mixture screw. There was just enough gunk built up in those passages that at least 1-2 of the holes were partially clogged on each carb(ITB's on a 4 cyl). It was causing the mixture to be just inconsistent enough to not start with a battery thats starting to get weak. And the passages that feed extra fuel when the choke is on were also a bit dirty.



Bottom line, if this bike doesnt get run weekly, the carbs get dirty.

Yeah, my KZ-400 has Keihin carbs on it too, and it seems I'm always fiddling with them.