Gas Leak - Help please

Hi all,
There is a small black tube running out of the bottom of the black plastic box that is just forward of the air cleaner. There is gas leaking out of this tube. Sometimes it is just a drip every 5 seconds or so, and sometimes gas streams out of it for awhile. It doesn't seem to leak when the bike is running or for sometime after the bike is shut off. I don't even see how gas can get into the box to leak out of this tube. The bike seems to run just fine, and doesn't leak after every ride, just most of the time.
I would REALLY appreciate any help - my wife won't let me keep the bike in the garage with the leaking.
Thanks,
Nitwit
P.S. You might be able to tell that I don't know a lot about motorcycles.
1980 KZ 550 LTD

The gas is overflowing out of the intakes. Most likely because your vacuum petcock has failed and is allowing fuel to flow down the vacuum tube.

I'll do some more checking and get back to you in a minute.


KZCSI

Yes, that bike has a vacuum operated petcock. While there could be several other reasons why you're loosing fuel, that's where I'd look first.

Here's how I'd check it out:

Remove the vacuum line from the back of the petcock. Is there gas dripping from the connection? If so that's the problem. If not cap off both the tube and the connection on the petcock. Next, remove the fuel line from the petcock. Does the gas continue to drip? If it does you could also have a problem with the float valves in the carbs. While the float valves do meter the amount of fuel allowed into the float bowls they aren't very good at blocking fuel flow over long periods of time. If the float bowls are over filling you will also see the leakage you have described.

You will be able to operate the bike using the prime position even with the vacuum line disconnected. That way you will be able to confirm that you've got a handle on the issue.

Before that, however, I'd check the oil for the presence of gas there's a good possibility that the gas has also been running into the engine.

I haven't had much luck repairing petcocks. If you can't find a new one, I suggest that you replace it with an aftermarket unit. There're plenty to choose from.

Hope this helps.

KZCSI

can the vaccum assist petcock be replaced with a regular petcock?? I know you would have to make a mounting plate to thread the new petcock into if you are using a stock tank.
I just wonder if the vaccum line can be eleminated?

Sure, the vacuum feature isn't necessary. I replaced mine with a Pingle petcock for which they make several types of adapters. It fit up to the tank just like the stock unit. I'll pull my paperwork and post a link.

KZCSI

Later:

I purchased a 3/8" NPT Adapter Plate from www.pingleonline.com . It fits to the Kawasaki tank and to the Pingle petcock. Worked sweet. I wouldn't say it was cheap, cost me about $100.00 for the adapter and the petcock.

All Pingle products are made in the US of A.

KZCSI

Pingle makes a variety of adapter plates. Most Kawasakis (not all!) use 44mm offset between mount holes. You just bolt the adapter plate on after opening up the hole the old petcock fitted into. The adapter plate has a 3/8" NPT hole which is the thread size of virtually all petcocks. Harleys use the same size so you can use a Custom Chrome, Drag Specialties or other Harley style petcock or you can use the more expensive (and better quality) Pingle petcock. www.z1enterprises.com sells the adapter plate and both types of petcocks (Pingle and less expensive types). You will need to measure the offset between your mount bolts on your tank. On one of my tanks, the offset was not the same as any of the offsets Pingle sold so I bought a blank adapter plate. It had no mount holes drilled but did have the 3/8" NPT threaded hole in the center. I drilled my own holes for mounting.