Boxerworks.com

Hello, new to the airheads. I have a 1981 BMW r100 that was in the family. Rode well last summer after being garaged for many years. Just needed new tires, a battery, and a tune up.

I noticed last summer that the left cylinder head would have a small leak (slow occasional drip) for several hours while it cooled down after riding. No oil leak when running. It's from the further gasket closest to the spark plugs.

I was told the valve cover may be warped, so that was replaced. Then I was told the cylinder head itself is warped.

Is this common? Is the solution to have the head decked? If that is the ultimate solution should I have both sides done?

Are there any temporary solutions? Double gasket? Aftermarket gasket? Anything?


Also, brakes. How difficult is replacing the rear drums? Never worked on a shaft drive. Any tips?

Valve covers may get warped through being overtightened. When every thing is right they seal with just a few ftlbs, little more than finger tight really. The centre stud is prone to pulling it's threads due to being a touch too short and insufficient engagement in the head so you need to go easy on tightening. Best to have more threads engaged in the head and less on the steel nut which can cope better.

Double gaskets is an option as is an after market silicone gasket.

Rear brakes shoes are easy enough to replace just beware the springs are very strong. To re-fit, engage the springs in the shoes and snap them back in a butterfly motion. Rear shoes last a very long time if not contaminated with oil, why do you think they need replacing ?

so you had asked about changing the brake "drum".
Changing the wear surface of the drum is a big deal.
I'm assuming you haven't removed the wheel to measure the drum diameter to determine if it's still within wear tolerances. As barryh asked, why are you asking? Are you having problems specific to the rear brake. As a point of reference, they are pretty weak brakes to begin with so don't expect a lot.

None of my airheads have leaked out of the valve cover. I use 1 stock gasket with no sealant, but there is no reason why you can't use some sealant. I've had good luck with the black hi-temp silicone seal in other applications. I would only use 2 gaskets if you have some other structural problems, as it just creates another junction for the oil to leak from. And as barryh said, don't over-tighten the nuts, especially the center one.

Good luck.

I've had luck with putting a thin layer of silicone gasket sealant on both sides of the stock gasket and letting it cure completely before assembly.

Thank you for the responses. To further clarify, I had max BMW diagnose the leak and determine it was the head itself that is warped.

I'll try some hi-temp sealant fully cured on both sides of the gasket and see if that changes anything. Any draw backs to an aftermarket silicone gasket?

In regards to the rear drum, it has just about zero breaking power. When the brake is depressed the mechanics all work to depress it, however, little to no breaking power is created. Significant change since when I started to ride it last spring. I'm assuming the braking surface will be ok. More so just need new shoes. They have been sitting for a number of years prior to this year.

Here is a link to Real Gaskets who make silicon gaskets for these bikes. Trick is not not over tighten on installation.

http://www.realgaskets.com/files/motorcycle.htm

Try switching to the Ferodo shoes Vintage Brake sells. The original shoes are hard as rock with the friction coefficient of granite on steel... With the Ferodos, I can stop my bikes with the rear brake alone!

jagarra wrote: ↑Tue Feb 28, 2017 10:35 am Here is a link to Real Gaskets who make silicon gaskets for these bikes. Trick is not not over tighten on installation.

http://www.realgaskets.com/files/motorcycle.htm

There are 2 gaskets listed -- which one is the silicone one?

Go back and click on their home page link. Seems everything they make is silicone except where they indicate it is nitrile.

I'm surprised that no one has come up with a gasket material, somewhere in between cement sheet and spaghetti.