1982 Yamaha XJ750 Maxim -Oil squirting into air filter box?

Question

Back in 1991 my very pregnant wife and I took a 100 mile ride on a very hot day. We made a couple of stops and the bike ran fine. A few days later I tried starting it (4 seconds crank, about 10 seconds wait etc.). After about 10 attempts , a few ounces of oil squirted into the air filter box. I didn't have time to fix it , so I drained the gas , oiled the cylinders and put it away for the winter. Well 17 years, and a couple of kids later,

it's still sitting in my garage un-repaired. It's only got 14K miles and still looks great. Has anyone had a similar problem and what was the cause and the fix? I don't know if it's relevant but the bike has an after-market oil-cooler.

Answer 1

I had the same motorcycle but a 1984.  Its seem that I over filled the oil.  It normally take I believe it take 3 3/4 qt of oil and I decided to use all 4 qt.  

Try filling it at proper amount of oil, I am not sure how much you oil cooler hold, but shouldn't be very much.

good luck and enjoy your ride!

Answer 2

Your crank case vents into your air filter box.

Could be a couple of things...one, you may have the bike over filled with oil. But if you didn't change anything after you rode 100 miles..didn't add oil ETC then why would it just all of a sudden do it?

Second.. could be some type of restriction in your air box..air filter may be excessively dirty..that would cause the bike to not start...and since there would be restriction..the piston draw would create a suction and could possibly draw oil into your air box while attempting to suck air.

Or, the after market oil cooler could be raising the oil pressure in the crank case causing it to squirt up through the crank case vent.

The bike has been sitting for 17 years? change the oil, air filter, plugs...  Put fresh gas in it, add some high quality fuel system cleaner..

Its probably going to need tires..I would change the fuel line just to be safe...dry rot.

Good luck, I cant think of what it could be other then what I listed... could be a broken piston ring or somthing of that nature, that would cause it to blow by the piston and pressurize the crank case enough to force oil out.