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Hey, I have a 79 KZ650 and one of the carbs is dumping gas into the motor. The bike runs fine though? It might be doing it when it's not running. I was thinking the needle and seat or the float is stuck. Any suggestions. As I said the bike runs fine so I'm thinking the needle and seat are bad and when the bike is running it's eating enough gas, but when parked it just keeps on dumping it it my motor. Does that sound right?

Thanks, Vach

Oh, one more question. If one of the air mixture screws has been over tightend what could happen? Hard to sink carb? leaking air around the screw? Won't effect the gas dumping though right?

It's possible that the float is stuck, or the float needle is worn and/or there is debris stuck in the needle seat.

Even if any of the above are found to be the culprit, it still should only fill that carb with whatever fuel is in the line after the bike is shut off.
So if it's dumping enough fuel into the cylinder to literally flood it, then chances are that your petcock is also leaking.

The way to check for a leaking petcock is like so:
With the bike shut off and the petcock lever set to either RUN or RESERVE, pull the fuel line off of the fitting.
If it still flows fuel, or even leaks slightly out of that fitting, then you'll either need to rebuild it (a waste of time & money IMHO) or buy a NOS petcock.

I had leaking problems on my 79 650 from both the worn out petcock, and the worn out o-rings on the three tubes that link the carbs' gas supplies together. (The center 'tube' that links carbs 2 and three is a T fitting that also connects to the fuel petcock from the gas tank. The 'tubes' between one and two, and three and four are straight. Each terminal has two O-rings which means that there are 12 O-rings to replace altogether if you choose to do so.)

I originally thought I had a stuck float bowl as well. Turns out I had been wrong.

If I remember correctly there are hose fittings on the carb overflows right? You could test to see if it is only a stuck float bowl by connecting some plastic tubing to the overflows to channel the possible float bowl dumped gas off away from the top of the motor.

If you do connect hoses and gas still dumps on top of the block, then you would know to look elsewhere first for the gas leak, saving possibly unnecessary carb float bowl rebuilds.

My bet is that the gas is leaking somewhere from the tank to the float bowls. (Petcock, pipe fittings, old gas line, hose clamp problems and such.)

Qdude- I think your talking about gas leaking on my motor. It's leaking internally. One of the carbs is not shutting off completely and I think when the bike is off it's just dumping gas into the cylinder. If I fill up with oil and wait a couple of days, it is filling up my crank case. The needle and seats are relatively new and appear to be clean. The bike runs fine, not skipping a beat. If the float was off wouln't the bike flood when running? Maybe one of the needle and seats just aren't seating even though they are kindof new?

I see, yes I was mistaken.

I think that it is possible for the engine to run well even with a stuck open float bowl valve.

There is a good chance that it is a finicky float adjustment.

I will say that my experience adjusting the float bowls on my 650 was the most difficult one I've ever done. I went through about a gallon of gas.

Best of luck with the project.