runs poorly 1980 kz750

My bike is running now but has absolutely no top end after riding for a minute, it seems to be starving for fuel, I replaced the float needles and rebuilt the petcock, however, I am not sure how to set the float level, it says that you have to use a special tool in the service manual and I dont have that.

Twin or 4 cylinder ?

rrob3112 wrote:

...I am not sure how to set the float level, it says that you have to use a special tool in the service manual and I dont have that.

Hello, and welcome rrob. Make sure to put relevant bike model info in your profile.

Regarding the float level, there are quite a few threads on that in the forum, just do a search. Also, you can search the old version of our forum, now called the Archive, by clicking on "Forum --> Archive" above.

Once you've done that, if you still have questions, we'll be glad to help!

My bike is a kz750 4 cyl, one of the carbs seems to be flooding one of the cylinders when it is shut off so when you restart it it will hydrolock and I consequently destroyed the starter clutch I think.

You have Keihin CV34s carbs on your 750. Set the fuel level to 1/8" below the gasket mating line. Connect a clear plastic hose to a drain nipple and hold the hose next to the side of one of the outside carbs while having leveled the carbs. Turn on the gas and open the drain screw. Gas will fill the hose...tap out any air bubble trapped in the hose. When the gas settles, that is the level it will be in the carb bowl. Turn off the gas, drain the bowl and remove it and bend the little flap of metal OVER THE float needle to adjust the height. Bending UP (carbs on bike) will lessen the amount of gas in the bowl and DOWN will allow more. Bend only a LITTLE as a little makes a big difference. Take your time as this can be a frustrating experience if you don't do the float level thing all the time.

I really doubt that the float level issue is causing the top end problem on your bike. Are you using the stock pipes and airbox? More info is needed to sort this out. What jetting are you using?

Last, the flooding is overflow when the bike is parked. I think you have a vacuum actuated petcock and your vacuum diaphragm is either buggered or you have a bad connection between the carbs and petcock via the vacuum hose. Check that connection and fix the petcock as I assume this overflow occurs with the bike parked. Also park on the centerstand as the overflow is likely out of #1 (low carb) and change your oil as it is likely fouled with gas. You might also have to change your air cleaner element if you have pod filters or the stock filter... just inspect it closely to ensure it isn't fouled or ruined from gas soaking.