Hey guys,

I am just wondering what exactly that little hole under the engine is where the tiniest amount of oil will drip out, not enough to even drip on my garage floor, just enough to notice it and to form a little drop which doesn't fall (although it probably does while riding). My questions are what kind of oil is this, why is this hole there, how much if any is normal to drip out? The picture was taken from the left side of the bike and the hole is in front of the centerstand and behind the sump cover.

Possible causes in the (usually occurs) in the following order:

1. O-ring behind the clutch basket, hardens and cracks caused by age and heat cycles......clutch would start to slip.
2. Sealing ring at clutch....do not reach the clutch friction surfaces.
3. Sealing ring at gear box input.

Motor oil and gear oil have a quite different smell, and motor oil is usually darker (after some use).

Inge K.

Hi FreebaserSF,

I'm afraid that the seal behind the clutch is leaking.

That tiny hole you've seen has the job of leaving out any possible oil leaked from the gear box as a prevention of clutch flooding.

I wouldn't worry if the amount of oil leaked were as little as you say but, there's no doubt that in a middle term you'll have to take off the gear box for sure, and replace the clutch and the seal.

I hope this can helps you.

If you want to rectify the problem then you will need to remove the gearbox. In my opinion if the clutch is working OK and there is no significant oil loss then just keep an eye on it in case it gets worse but bear in mind you will need to do the job in the near future so plan for it and do it when it is your decision and not when the clutch starts slipping well away from home.

The clutch is working just fine as far as I can tell. I think it is engine oil based on color and smell. It seems extremely minor whatever it may be. How long would it take someone proficient to pull off the gear box and possibly replace a seal?

Probably something like 5 hours plus the seal and O ring and do the spline lube at the same time.

The BIRV, the bmw incontenance relief valve. , well if they age like horses they're 150 odd year old, there's bound to be a few dribbles.

beanoldboy wrote:The BIRV, the bmw incontenance relief valve. , well if they age like horses they're 150 odd year old, there's bound to be a few dribbles.

Very good beanoldboy very good indeed.

BIG D