Oil in airbox

[suzukizone]

My 81 GS 850 G collects oil in the airbox sufficient to run out onto the LH engine case. I believe it may be coming from the vent hose coming off the valve cover. Any tips as to why? Bike has 29kk miles. Did this since I got it at 20k.
Thanks:

[RotaryRodder]

lots of blowby?

have you done a compression or leakdown test?

[ptm]

Another possibility is that there is too much oil on the foam air filter. On my 750 and 850 there is a drain hose from the airbox that runs down by the center stand. At least that keeps the excess oil off the engine.

[RotaryRodder]

also, if its overfilled with oil, the vent will shoot oil into the airbox.

[mark]

There is a wrapped wire sort of thing under where the breather tube connects to the top of you engine. If you take off the 4 bolts that connect your breather tube assembly to the motor you can see if its still there. I assume that wrapping is in there to catch excess motor oil and allow it to drop back into the motor. The PO may have taken it out for some reason and that might contribute to your problem.

[suzukizone]

Thanks for replies. Have not done compression test or leakdown. Can do the first here at home, I work part time @ a Suzuki dealer so perhaps I can borrow implements from the boss for the leadown.

Only extra oil in filter area is the excess engine oil that shows up there.

RE: Overfilling. I had not filled eng oil to top level after an oil change & even let it run a bit low but still got overflow into the airbox. I have used a bubble or straight carpenter's level to be sure that the bike is level when on centerstand & on my lift. Every way I check it the bike is perfectly level when on the centerstand so the reading I get from sight glass is reliable when on lift.

The metal "brillo-like" material is definitely there up top side & looking rather like new, not butchered up or the like.

I was thinking of capturing the top breather hose into some container to be sure that is the source of the oil. It is really quite a mess after 50-100 miles.

Any other tips certainly appreciated.

DH