Gas/Oil mixture shooting from crankcase vent!

[Bobber]

This is my project bike 81 GS 450L. I havent done much riding on it, maybe 10 miles (Purchased this bike over the winter). Ive rebuilt the carbs and done some electrical work to get it on the road, but other than that the bike has basically been untouched for a long while. The previous owner told me the bike has sat inside for the last 5 years. It was in his living room when I went to look at it.

I cleaned and rebuilt the carbs, then rode the bike for a few days to work. I noticed a small oil leak behind the front sprocket cover so I replaced every seal in that area. Run the bike for awhile and everything seems fine, so I go for a test ride. Im cruising about 45mph when I go around a slight left turn in the road when I find myself sliding sideways down a four lane highway. I managed to get the bike to the side of the road, shiny side up. The entire rear of the bike and my entire back is covered in oil. I limp the bike home and put it on the centerstand and run it through the gears.

At first there is no problem, bike runs goods and isnt leaking any oil. Then all of a sudden watery oil comes shooting from the top crankcase vent. Its not a trickle my any means, its is a full blown geiser. It filled an empty beer bottle in about 3 seconds. I thought it was pure gas, but when I was looking for the first oil leak I put in UV dye, and the dye shows up in the fluid coming from the vent. I drained the oil in the motor and the same oil/gas mix was in the crankcase, and I drained more than a gallon. Should this bike even hold that much fluid?

My Theory: When I rebuilt my carbs I "eye-balled" the float height. (I know I know, dont yell at me) Im thinking I either have a float height way off or a needle stuck open causing gas the poor into the crankcase. Whats throwing me off is that the oil is coming from the crankcase vent and not the exhuast. There is no oil coming from the exhuast so I dont think it is being pushed past the rings. Im not sure how these engines are designed, would too much fluid in the crankcase allow the fluid to escape through the crankcase vent?

And Input would be much appreciated! This one has gotten me perplaxed. And... does anyone know the height for my model? The carbs are 34mm Mikuni's.

 

[Macmatic]

Have you checked the oil level? Is it way over full and smells like gas? Then yep, stuck needle or something along those lines. If you have the OEM type petcock on there don't leave it set on PRI or prime, this lets fuel flow all the time instead of only when the engine is running.

/\/\ac

 

[BassCliff]

Hi,

Have a look at some notes I've collected.

[FONT=Trebuchet MS, sans-serif]Overflowing Carbs[/FONT]


Thank you for your indulgence,

BassCliff

 

[Bobber]

Ive come to the conclusion it is a combination of my carbs and the petcock. Ive had carbs on my Katana spew fuel, normally into the air box, but they never filled an entire engine. Im going to set the float height and replace the needle and seats (Like I should have done to begin with.)

The oil leak is what confused me, I was looking for bad gaskets, not carb issues, but after drianing the engine oil it is defenitely gas in the oil. Guess Ill go back to the basics. I appreciate you guys giving some input!

--Does anyone sell an aftermarket petcock with an "off position"? I know I shouldnt need it if my floats are correct, but the bike sits alot and Id like to be able to turn the fuel off if I need to.

 

[Macmatic]

I haven't ever actually seen one but I believe Pingle petcocks are ON/OFF only.

/\/\ac

 

[Baatfam]

--Does anyone sell an aftermarket petcock with an "off position"? I know I shouldnt need it if my floats are correct, but the bike sits alot and Id like to be able to turn the fuel off if I need to.

Yes...Pingals are on/off/res...
But the factory petcock is technically off when the motor is not running...
If the petcock is working correctly, it won't pass fuel without engine vacuum.

 

[kamesama980]

for the gas to get into the crankcase, it's seeping past the rings. they're probably sticking from sitting in the living room for 5 years. to have that much is a fairly large problem.