Gas in oil

Hey all. I recently purchased a 1983 KZ550 M1 LTD. This is my first bike. The problem is I'm continuing to get gas in my oil. I noticed this when I accidentally rode with the choke half out for about 10 miles one day. Upon discovery of this mistake, I drained the gas contaminated oil from the bike and replaced the oil and oil filter. After a few more rides I got paranoid that the oil still had some residual gas in it, so I replaced it again, along with new spark plugs since the old ones had substantial carbon deposits on them. After a few more rides, I checked the oil level. It seems to have risen slightly again, and it still smelled like gas. The new spark plugs were already getting black at the tips. So I now know I have too much gas going into the cylinders for one reason or another and am getting the gas in my oil.

After some research, I suspected faulty petcock. Mine is a vacuum assisted petcock. So, I removed the fuel line. With the petcock set to ON, no fuel flowed until I rocked the tank a little, and a couple drops of gas came out. I then removed the vacuum line, and took the tank off. Currently, no gas flows freely, but if I let the tank sit, then pick it up and slosh the remaining gas back and forth, a few drops will leak out.

I was expecting gas to flow freely from the petcock, if the petcock was in fact the culprit. I guess my question is this: Are these few drips here and there enough to get gas down into the crankcase and mix with the oil, or do you guys think there might be other suspect factors?

Any suggestions would be helpful!

"...do you guys think there might be other suspect factors?"

That depends. Do any of the carbs leak or drip after you've just finished a trip?

I've never had much luck rebuilding a petcock. If you're not really a stickler about OEM parts, I suggest anything made by Pingle. They're still made in the USA, believe it or not. I just plug off the vacuum line to the petcock. A lot of these old Kaws have fuel system problems because many of the old parts are made from real rubber, which is softened by alcohol.

I'm still trying to find out why the Govm'nt thinks it's better to burn alcohol than drink it. Most likely, if I ever do find the answer, they'll kill me.

KZCSI

Perhaps you are looking at this issue wrong... combustion is poor. You then foul plugs and get mis-fires. The carbs will continue to belch gas into the combustion chamber. If there is a mis-fire, the combustion chamber can flood while the cylinder is now non-firing. The gas will run down into your crankcase as it is easy for gas to get by the piston rings.

Why is the bike mis-firing? Have you checked compression yet? Have you adjusted the valves? Checked coil voltages? ANY of these things will produce lousy combustion as will old tired coils or bad ignition wires/caps.

If your vacuum diaphragm in the petcock is compromised, you can certainly drool extra gas but this will flood the combustion chambers when the bike is sitting and not while it is running. When running, a healthy bike will just burn the gas supplied which is being metered by the float seat/valve. If you want to test the petcock, put a jar under it while the vacuum hose is disconnected. If you get a few drops, this won't foul the oil. I suggest you look at tuning the bike up and a good way to start is to buy a shop manual and also look at diagnosis tools like a compression tester and a multimeter.

KZCSI wrote:

"...do you guys think there might be other suspect factors?"

That depends. Do any of the carbs leak or drip after you've just finished a trip?

Nope. No leaks anywhere.

wiredgeorge wrote:

I suggest you look at tuning the bike up and a good way to start is to buy a shop manual and also look at diagnosis tools like a compression tester and a multimeter.

I'll get on this. Thanks.

Ive rebuilt several petcocks both regular & vacuum with no problems except the price tag for OEM kits of about $35 for the last vacuum one. I too dont believe thats your main problem though. Pingels are also first class too

A couple of drips will not flood your crankcase. It's the running rich fouling some cycles and fogging the innards. Get it all dialed in, a tune up, then give her a good run out. She'll thank you for it.

Not familier with I believe CV carbs? How about stuck or out of adjustment floats?