two crankcase vents gs850

[floydthedog]

I have a 81 gs850 and have heard a lot of discussion on crankcase vents and case pressure and the perils of overfilling the oil. I have done this on my bike and have noticed a crankcase weep hole in the case under the trans.cover on the side of the case. the hole is machined about 5/16 " in the 2" x 1" indent on the roof of the opening. when my oil was overfilled and I ran it hot pressure built up and this is where the oil came out and weep ed onto the exhaust brace right above the drain plug, so if gas gets in the oil due to bad needle seats ( and this has happened to me also ) this is where it weeps. And after the oil level reaches a normal level it stops leaking.
granted i have changed out vacuum carbs for manual and use pods , so there is no vacuum to draw oil into an air box which i don't have.
I just bring it up because i can't be the only one with this hole in the case and I haven"t seen any post on this.

[Steve]

The only crankcase vent I am aware of is the one on top of the valve cover that has a hose leading to the airbox.

I have an '81 850 apart in the garage right now, so will have to follow your description of the vent and look for it.

.

[BassCliff]

Hi Mr. floydthedog,

Are you talking about the crankcase or the bevel gear case? Check out the pictures in this thread. The "mystery hole" in question is where the breather line for the bevel gear case drains, under the starter and out the hole in the bottom of the case under the left side engine cover.

Thank you for your indulgence,

BassCliff

[bwringer]

The mystery hole is also where oil drains out if the o-ring on the nose of the starter gets old and cracked.

This has happened to lots of folks, often after removing and replacing the starter, and it's baffling unless you've already traced the origins of the mystery hole.