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RickR90s
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Farmington Hills, MI
Joined: 11/28/2016
Posts: 63

I've done a few pushrod seal replacements over the years and always sealed the rubbers.

I have some weepage on my '74 R90s so another job is coming up. Previous replacement was about 7 years ago and I used a Loctite product that is some sort of a flexible material (non-hardening gasket sealer).

The bike has stainless pushrod tubes, and 136k miles.

What's the conventional wisdom on gasket sealer for the rubbers?

Yes?
No?

Use rubbing alcohol to clean them per Chris Harris' video's
Permatex?
Yamabond?
Hylomar?

Thanks,

RickR90s

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RickR90s

schrader7032
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VBMWMO #7032
San Antonio, TX
Joined: 10/27/2006
Posts: 6333
Snowbum prefers engine

Snowbum prefers engine oil:

http://bmwmotorcycletech.info/pushrodseals.htm

What should keep them from weeping is the proper placement, how they are drawn down into the holes, and the use of the correct torque.

I've used Permatex Ultra Gray as a thin coat on the cylinder base, avoiding excess around the upper two stud oil orifices.

Be very wary of Harris' videos and approaches. I've had more than enough "gurus" declare him a serious problem with the details of Airhead maintenance. It might be worth watching to get an understanding and visualization of the jobs, but look elsewhere for confirmation. I've just found a number of youtube videos by Moto Phoenix...well worth watching. BTW...Oak Okleshen sells a book on performing a top end. Unfortunately, he passed away recently, but I'm sure someone will be picking up the mantel to sell his top end book.

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Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

mark_weiss
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Arizona
Joined: 11/16/2013
Posts: 170
I've done a lot of top ends.

I've done a lot of top ends. I use a thin layer of grease on the pushrod seals. This is not to act as sealant, but to lubricate the rubber pieces so that they seat properly in their sockets. I do use a small amount of silicone sealant on the pushrod tube, this is to stick the pushrod seals in place and keep them from rotating during assembly.

Check that the seal compressing rings have not slid up the pushrod tubes. A straight edge laid across the cylinder base should just contact the edge of the ring.

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Mark
qualitycycleservice.com

RickR90s
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Farmington Hills, MI
Joined: 11/28/2016
Posts: 63
Great advice. Thanks

Great advice. Thanks everyone!

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RickR90s

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