Clutch slippage

[Stappenbeck]

'79 BMW R100RT. Had not ridden except for short trouble - free trip over mountain pass last year. I warmed it up over 15 mi. everything fine. Then I turned around to go back to town. I gunned it and was going thru the gears fast. Suddenly lost power RPM 5000 but slowed to 30 mph. Went slow for awhile then clutch seemed to grab again. No problems after this. Did I smoke the clutch? What can I do to keep this from happening again? Is my clutch bad, or am I bad for gunning it?
Kurt in Montana

[108625]

I don't know, does it look like this?

[108625]

Or this?

[Stappenbeck]

Ouch!! I hope not. Is there a way I can check it without tearing it apart?

[108625]

That was a catastrophic rear-main seal failure. Look for oil on top of the sump, under the transmission. If all is dry, check your cable adjustment.

I have had a separate, and similar experience, to the one you described as well...
On one of our windier days, I was doing fine one direction, then I turned into it. Holy cow, I was held to a terminal velocity of around 65, and it was a struggle to get there. Then a series of stiff gust literally overpowered the weak link (clutch) and the bike behaved exactly the same; over-rev and loss of momentum.

If you can't find anything obvious wrong, I'd try a test ride close to home, and pay attention to the smell. I wouldn't ride it far until I got to the bottom of it, or else you might be calling a tow truck. Trust me.

[PGlaves]

First, make sure there is adequate free play in the clutch cable. Then make sure that everything feels smooth and that when you release the lever everything is returning to the engaged position with no binding.

Then look at the "cup" where the casting extends rearward. Oil puddled at this location would indicate a leak of either engine oil or transmission gear oil which could foul the clutch.

If this provides no clues as to the cause then it is possible that the clutch disk has simply worn beyond usable limits and needs to be replaced. How many miles on the bike? On the clutch?

[crazydrummerdude]

First, make sure there is adequate free play in the clutch cable.

A cable adjustment fixed my slipping in 2007(?). Super easy.

[Stappenbeck]

Thanks Bob, PGlaves, & crazydrummerdude,
Cluch adjustment fixed it. Not enough free play. Same thing with my life. Quite a relief after seeing those pics from Bob. Tomorrow I have to flush all that silicone brake fluid out and replace it with dot 4. Its great to be out riding again!!!
Tito