I came back yesterday from a 300km trip on a fast road with little bumps, I parked my bike in my garage and everything was ok. But this morning I noticed a few drops of oil (5 or 6) on the floor under my bike...I thought it was the engine but when I was inspecting the bike I noticed they came from the rear shock....a very dark and light oil...

Why? what to do?

I must say  I was riding with my girlfriend (me : 65k she 56k Luggage: 5K Total 126 K on the bike) at high speeds.

Thank you all.

It seems that your rear shock is loosing it's oil. You will have to change it because when the oil is gone there is no damping, so that's pretty dangerous. I don't know if the standard shock can be rebuilt, maybe someone here knows.

Anyway, the weight you put on it is definitely not the cause of this as I have traveled with my brother + luggage for 1500 miles. (me with gear on=80kg, brother with gear on=70kg, luggage = 35kg: total = 185 kg) That's a lot of weight, but never gave any problems. Cornering was still great and even downhill at 100mph it was stable!

I don't think you're gonna be able to re-build the OEM shock without a hacksaw & a welder.  I had an extra one that I cut apart (long winter + tools available + nothing else to do = lotsa things get "experimented" with...).  The bottom of the shock (where the shaft goes into the body) is welded shut.
Best to just find another one in good shape, or better yet, upgrade per the suggestions elsewhere on this site.

you can just upgrade your shock.. it would be lesser of a hassle.. if your running stock shock you can have mine for the shipping cost, mine is an '01.

I have a GS shock. Well if you want it say $10 + shipping.
BTW I dont think its your shock. I have very rarely seen shocks go especially on the GS. There has been the very rare Fox or Ohlins that has given up.
I think your engine has sent some blow by into the airbox and that is dripping down the drain tube at the bottom of the airbox.
So see if the airbox has more liquid in it and check that hose that looks like it has a cap on it as well.
Cool.
Srinath.

How do you know you have not had blow by...The airbox is designed to collect and hold it. Your bike may have just had some blow by which it drained now. You could drain it all out and clamp the hole back and see how much it collects in a 100 miles or whenever. Also dont take off the air filter to check it. You get a plastic cup and catch it from the hose by squeezing it or some like that. I dont remember cos I tossed that hose and air box a long time ago.
Cool.
Srinath.

My 89' did the same thing until I chucked the air box.  Gas blowing back from the carb collects and with the slight amount of dirt inside the air box, and the fuel drying out a little, it came out like a thin maple syrup.

I'm like you - I can't stand a leaker.  I'll go out of my skull until I fix it.

Paul

After thought - I think you're correct Srinath.  It must be the blow by from the breather tube collecting in the box.  I think the little bit of blow-back from the carb may help thin it out, but most of it comes from the crank case.

Paul

There need not be any carb overflow to thin it out...The part that blows by is a pretty random mix of intake charge (gas and air, combustion by products Carbon, Co2 and water and oil) Of these water, carbon and oil are the only ones that wont evaporate or are gasses already.
Cool.
Srinath.