/7 pushrod tube replacement

Never heard about that Permatex product but Ultra Gray by Permatex is often a suggestion. Hylomar has been used in the past. Another that I recall is something called Yamabond as well as Driebond. Here's a couple of sites that discuss seal replacement:

http://www.pbase.com/dqmohan/prtseals

http://www.gunsmoke.com/motorcycling/r100gs/pushrod_tubes/index.html

I looked through the manual I got from Oak and I could not see any reference to pushrod tube height. Maybe I missed it but I looked several times and could not find it.
I might have used the wrong seals because it was just too tight when I put the cylinders back on.

I looked at my manual a few days as well...didn't see it. I got that information from a diagram that Oak mentioned on the Airmail email list about 10 years ago. I asked him to send me a copy. Rather than reuse his "art work", I created my own. Nonetheless, the stop ring position that's been offered here is what he suggested.

Where did you get the seals? What was the part number that you ordered them with?

I believe I got the seals from a and s cycles when I ordered the stainless pushrod tubes

A&S is a good place. As I mentioned above, for the same year bike, my part number was 11 32 1 262 995. A cross reference for this number shows they're used all the way back to the /5. From the range of models, it looks like it covers virtually all Airhead bikes. Hard to understand how you might have gotten the wrong part.

The first time I re-seated an airhead cylinder, I used Hylomar about the base of the cylinder. Leaks reappear eventually. The most recent time (upgrade to Nikasil cylinders on /7) I used Hondabond (same as Yamabond); no leaks thus far.

A friend with a /7 had persistent leaks from the set screws used in the drilled holes in the engine case for oil flow. Finally, he obtained some aluminum set screws from Re-Psycle BMW and installed these using Hondabond as a coating on the set screw threads. No more leaks. I believe that Matt Parkhouse was the one that recommended the Hondabond on the set screws.

I will get some hondabond for the next round.
It just seems to me that the pushrod tubes are in too far because they are really mashing the seals deforming them?
Upon close inspection the oil seems to be coming from where the cylinder contacts the block. I might have gotten impatient upon reassembly and put them together too quickly.
I could do the baby powder trick to be sure.

I just had a thought and a question. If I remember correctly is there a air valve kinda like a crankcase breather valve on top of the block that lets the pressure inside the crankcase out through one of the carbs? If this is blocked wouldn't the pressure inside the crankcase force oil out through the seals and gaskets???
Just asking?
Dave

Dave -

You're right...without the crankcase breather, that air has to go somewhere. It will find paths of least resistance, so that means seals such as the pushrod (which you can see the results) and the rear main seal (where you can't readily see the leak until it gets too big).

part numbers

Actually not exactly right on the seals. /5s and /6s up to around 8 of 1975 use p/n 11 32 1 250 267. There was a change to the diameter of the tubes at that time (larger) that required a different seal (995) that was used thru the rest of airhead production.