K100 intake manifold rehab question

[billday]

I'm in the middle of rehabbing my K100 intakes.

Part No. 1 in this diagram http://www.maxbmwmotorcycles.com/fiche/Diagrams/B0000149.png?v=08102012 , the intake manifold or part no. 11 61 1 460 408, has an O-ring on the bottom. I definitely want to replace those O-rings, but the O-ring doesn't appear in Max's fiche. Is there anybody out there who has done this job on the K100 and can tell me where to find the right size O-ring? I tried my local Autozone and all they could suggest is cut-your-own gasket material.

The corresponding O-ring on the K1100 can be found and ordered from the fiche -- is it the same size? The 1100 manifold is a completely different design. In any case, don't suggest I just buy new manifolds -- they sell for $53.84 a piece!

Thanks guys,

Bill

[frankenduck]

You're looking for a part that doesn't exist.  The 2V boots don't have an O-ring like the 4V ones do.

[billday]

It sure looks like one. If that's not an O-ring, I'm glad I didn't try to dig it out of there.

The guy at Autozone suggested cutting my own gaskets from a thin gray material they sell for five bucks per sheet. Think there would be any benefit to doing that?

[frankenduck]

I know it's not what you want to hear but if I were going through all of that trouble then I'd probably install new manifolds.

15% discount: http://www.motobrick.com/index.php/topic,1680.0.html

[ReneZ]

If you think the boots are re-useable you can use a proper sealant on clean surfaces. Just remember that most running issues come from some air leakage between the AMM and the cylinders (except for the dirty electrical connections).

[billday]

Yeah, today I decided to give up on the search for replacement O-rings, and instead clean up the manifolds and the engine block and use a bit of RTV.

The auto parts guy I spoke to today told me he thinks the O-ring is cemented in (which would explain why it's not sold separately as with the K1100 manifold). (He had O-rings that were the right diameter, but too thick.)

BTW -- I emailed Max BMW to ask whether they could get me the O-ring, or some option other than $200+ for new manifolds. I got not one but two replies, one from the guy who deals with online orders and one from the parts manager. They couldn't help me, but they answered. Seems I'm often reading posts from guys who can't get any help from dealers for their classic K's, so I want to put in a good word for Max's.

[lukeman]

I replaced all the intake boots on my 85 k100 with brand new ones from Bob's BMW.  I thought there might be O-rings on there as well, but they don't exist and are only on the k1100 models.  The new boots have kind of a ribbed flange on the bottom that I assumed would seal once compressed by the bolts.  I've read a few places online that recommend putting some liquid gasket in there.  I think you're fine with just a high quality silicon gasket like Ultra Blue or something along those lines.