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My son and I just got our project bike on the road (1980 KZ550 LTD that we picked up for free as it had been garaged 20 years earlier when it failed to start). We received a ton of great advice from these boards over the past few months so a huge thanks for all the great content!

It's running great, but we're down to one last problem, which appears to be a very intermittent overflow on the left most carb. I'm not sure it's isolated to only that carb, but it seems to be. I checked the float height on all 4 with a homemade gauge and all seem correct. We have a new fuel filter so I'm expecting it's not contaminants jamming the needle. Wondering if people have some practical experience that would suggest a likely cause?

Thanks again for all the great responses, that bike would not be on the road without this board.

Rex

Post edited by: kevnrex, at: 2007/03/23 21:12

The carburetors fuel supply is regulated by the petcock. Folks who have overflow problems sometimes expect the float needles/seats to act as a fuel shut-off valve but this mechanism is for metering fuel to the bowl while the bike is running and the petcock is the means of stopping the flow while not running. If you have a gravity petcock is will say ON OFF RES. Turn it off when parking. Gas drains from the top three bowls and goes down the fuel pipe to the #1 carb and it WILL overflow. If you have a vacuum petcock, it is likely that the petcock is not functioning as it should. Next time you get a chance, pull the gas hose off the carb assembly and leave the petcock in the ON position. Put a gas can under the hose and see if you get any gas discharge. If so, the petcock diaphragm needs replacement. Kaw put this type petcock on all bikes in the late 70s so that owners didn't have to remember to shut off gas. Unfortunately, these petcocks are prone to failure and you WILL get dribble as a result while the bike is parked on sidestand. It is also a good practice to park on centerstand so that the carbs are fairly level which will also help stop leaking. If the carbs continue to leak, install new float needles after cleaning the seats with brasso and a q-tip and reset the float levels using the service fuel level method.

I did mean to mention that I have a non-stock/non-vaccuum petcock and learned that lesson about always shutting it off after several complaints about smell of gasoline smell in the garage. I'm suspecting the needle as I seem to recall noticing that the spring action on that one seemed weak.

Thanks for the help.