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Hey guys - since these are new covers, perhaps they are not "true" to the head, or maybe the heads themselves is not "true" (although I tend to doubt that they are warped). All I know is my /5 never leaked oil anywhere within the cylinder assembly, including at the cover gaskets. I guess I will use a dab of silicone grease on them and go from there.

Hot oil will wash grease out of a space between a gasket and hard parts. Put the valve covers on without a gasket to see if there is a visible gap between the hard parts. The head or the cover can be warped, that's one reason the cover gaskets are so thick.
If you crush the center strip of the gasket with the center bolt the two ends will tend to raise up. I lost one of my center nuts on a /5 motor in my conversion. It has run for years with only the two tiny end nuts holding the cover on.....no leaks!

Oh BTW, to my knowledge no nuts or bolts on a BMW airhead motor came with any thread locker from the factory.

George Ryals wrote:Oh BTW, to my knowledge no nuts or bolts on a BMW airhead motor came with any thread locker from the factory.

One of the reasons I like those wave washers.

Like George says, take the gasket out and look for a gap.
Holding a torch underneath makes it very easy to see gaps.
It could be the cover or the head.
Use a sheet of glass, wet+dry sand paper, WD40. Take the cover studs out and sand that sucker (figure 8's and periodically rotate 180 ) until the gasket surface has no low spots, not even little ones or 'nicks'

If there's still light after that, it'd be the head.

My original heads were bent by a machine shop when doing valve work. Enough to make my covers leak. I don't go there anymore.
Permatex 3 aviation sealant is excellent for use with cover gaskets.

It could be argued that I did worse to my heads before the machine shop got them.
OK, so no one's arguing.

Dave Backmarker wrote:Hudson,
There are no stupid questions. At the risk of incurring derision from my fellow airheads, I use a tiny bit of grease on both sides of the valve cover gaskets. In my defense, I learned this trick from a machinist back in the early '70's. Whenever I'm working with a low temp gasket surface that I know will be taken apart and put back together repeatedly, I use grease. Also, Ted Porter's Beemershop offers very nice gray gaskets (silicone?) that have worked well. And, I'm sure you tightened the valve cover nuts in something approaching a pattern to ensure the cover isn't slightly twisted.

DaveM
1975 R90S, 2000 R1100RT

+1, I use grease too on both sites of the valve cover gasket. It doesn't stick to any side and always comes off nicely.

Ahm ... with a center nut and two studs 180deg apart, there isn't much of a pattern, is there ! Center nut first is what I do, then the other two.

The "pattern" would be more of a technique. Put all three fasteners on finger tight, snug them all down half a turn at the time starting with the ends then the middle until they are all as tight.

One thing to note: comparing my old covers with the new ones, I see that the lip that presses against the gasket is taller than the lip on the older covers. I tried using two gaskets and it is just too thick with the new covers with the taller lip to thread and tighten the middle end cap fastener.

Question: Are the silicone gaskets just as thick as two gaskets? I ordered a set yesterday.

I didn't see any apparent gaps when inspecting the mating surfaces. But either the heads or the covers are not entirely true. Last night I used some gasket sealer on one gasket installed and let dry overnight. So far, no drips. Before it would drip overnight. Today, I will test it under pressure and take her out for a ride and see what happens.

Will keep you posted. Thanks everyone!

Hudson,
The gray silicone valve cover gaskets are about 2mm thick.

DaveM
1975 R90S, 2000 R1100RT

Sorry gents. I got everything up and running and been riding! : )

I put in the silicone gaskets and no more leak! Again, thanks for all the advice and insight!