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Old 04-20-2013, 05:49 AM   #1
Other Bob OP
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R80 valve stem seals?

Does someone make valve stem seals for the mono-era R80? Manufacturer, fitment, supplier, ... good/bad experiences?

Thanks,

Bob Farr
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Old 04-20-2013, 07:31 AM   #2
villageidiot
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I had the heads on my r100gs done by JR at angel city cycle in Los Angeles. He put new guides with valve seals in the heads. I had no complaints whatsoever with that decision. I do not know what they are, or what they come off of, but maybe you could call him and ask.

I also remember reading that the guides from a Yamaha sr500 are the same size as the airhead, but do your research before taking my word for it, it's been a while.
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Old 04-20-2013, 10:54 AM   #3
disston
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None of the Airheads use valve stem seals. If you are burning oil from leaky valve guides you need new valve guides and/or valves. I have heard of this being done but I have always been under the impression that it is not correct and is done by those that don't know the correct way to fix Airhead valves.
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Old 04-20-2013, 01:28 PM   #4
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Running guide seals has nothing to do with whether or not you know the 'correct' way to fix airhead valves. It has to do with how you want to run your engine. If I had a real hot rod and IF had the room for them, I would run them for performance gains. The real issue is what type of seal to use. The old rubber seals with a spring are junk compared to the newer teflon seals. I would not use rubber seals.
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Old 04-20-2013, 06:15 PM   #5
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My heads were done with viton seals. And new valves and guides. I don't think it's a "doesn't know how to set them up" reality is, most boxer engines like BMW and vw's don't use valve seals because 99% of the time the valve guide is not "submerged" in oil
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Old 04-20-2013, 06:39 PM   #6
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OP, your question did make me wonder- are you souping up an r80?

Pics required if so!
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Old 04-22-2013, 07:35 PM   #7
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Quote:
Originally Posted by ozmoses View Post
OP, your question did make me wonder- are you souping up an r80?

Pics required if so!
I'm not really souping it up, but I am trying to improve a few things. I had a little valve train trouble last fall -

http://advrider.com/forums/showthread.php?t=829938

While I have the engine down I'm going to add a Motorrad Elektrik 450w Omega alternator, Alpha ignition, a rebuilt starter, and rewire the bike with a Motogaget M-Unit controller. Call it project creep!

Then, to deal with the original problem (in addition to using proper oil with ZDDP), I found a company specializing in anti-galling abradable power coatings -

http://www.line2linecoatings.com/

I purchased a new 308-degree cam and lifters and had them coated -





Just for shits I had the piston skirts done too -



My goal in using the coatings is to provide some extra scuff/gall protection during initial cam/lifter break in, and perhaps some better wear characteristics on the lifter sides where they rotate in their bores.

As far as the valve stem seals are concerned, I'm not using them as a bandage for worn and leaky stem guides. Mine are still in spec and my oil consumption is acceptably low. But I know from my past experience with HD's (the other non-submerged guide, air cooled example - and even that tractor has roller lifters!) that even an in-spec engine can have its oil consumption improved by adding stem seals ... the engine is apart, now is a convenient time to add them, so I asked.*

There are some eBay sellers offering valve stem seals for K-bikes. This seller carries a lot of seals for various bikes -

http://www.ebay.com/sch/smw70ss/m.ht...p2047675.l2562

I don't yet know which, if any, will fit. I will probably end up taking some guide measurements and "compressed spring" measurements at max lift and then call the eBay seller to see if he has something close. Or maybe I'll just contact Kibblewhite directly ... if I can get something close I can easily make some small adjustments to the top end of the valve guide to accommodate the seal (lucky me, I have a small Moore jig borer).

That's the story and I'm sticking to it. If I find a useful drop-in valve stem seal I'll leave a note here with the part number. If the coating turn out to be an epic failure I'll report that too.

Bob

* I think that manufacturers make their design/engineering decisions for lots of reasons. Cost reduction, new engine break in considerations, warranty claim concerns ... everything is a compromise. What is best (mechanically) for an engine when new, and safest (financially) for BMW while still exposed to warranty claims, may not remain true once the engine is run in. And what was true about valve stem seals in 1985 may not be true about them in 2013 because of improvements in materials and design. So the choice not to use seals originally may represent no more than BMW playing the safer side of the reliability curve during the warranty period. "Burn a little oil? No big deal, they ALL do that!" By the time the guides are so worn that the bike smokes it is no longer BMW's problem.
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Old 04-22-2013, 08:03 PM   #8
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Youre not wrong in trying to reduce oil entering the compression chamber. More power, cleaner burn and reduced chance of detonating. Sounds like its all good!
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Old 04-23-2013, 06:37 AM   #9
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Motokaw-

I do remember your earlier thread now- it actually prompted me to give my lifters a look!

Seems your goal is to never have to revisit your bottom end again.

That coating is quite interesting.

Did you ever make any real determination of the initial cause for wear?
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Old 04-23-2013, 08:02 AM   #10
Other Bob OP
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Ozmoses,

Actually, I will be putting an eyeball (and probably a micrometer) on the cam and lifters pretty frequently for a while. The coating is supposed to burnish slightly (though quickly) to a close tolerance fit, leaving a coated surface which is itself slippery and which also retains some lubricant to help form the hydrostatic oil bearing that keeps our parts from metal-to-metal galling. I'll record the measurements before assembly and at each inspection, including photos (posted here, of course).

I expect that the most noticeable (i.e., measurable) burnishing process will happen very quickly during the first few minutes of run in. The first inspection should show the largest change, with the measurable wear stabilizing quickly after that. I've considered checking initially at 25-50 miles, then every 50-100 after that until I see either a failure-in-progress or a stabilization of wear .

I have a trip planned with friends in late June through upstate NY, PA, of about 1,500 miles, so there would probably be 3-4 inspections before the trip and one on return over the course of about 2,000 miles to see if these coatings are snake oil or worthwhile. What do you think of that inspection schedule?

As far as a "real determination" of the initial failure, I'm not sure how I could achieve that. I would have to identify, interview and force a confession of poor maintenance from some previous owner. I purchased the bike last summer from an inmate here, who had only owned the bike for about two months himself. He had purchased it from a long period of non use, got it running, and flipped it to me with fresh oil and in fair running order. When I discovered the damage I initially suspected that the period of storage had permitted the cam and lifter to pit from corrosion and then gall when started again. But I now suspect that the owner before and during storage used automotive oil without ZDDP additives instead of motorcycle oil with the Zinc content, which allowed the galling over the time before storage.

I have no beef with the inmate I purchased the bike from. He didn't own/operate the machine long enough to cause the damage observed, and he didn't misrepresent the bike. I do have some beef with BMW's lifter design though. Solid lifters rotated in their bores by an center-offset and taper-ground cam lobe is IMHO a really poor design choice. It is inevitable that the sliding surfaces will suffer higher wear than cam lobes and lifters of other designs, like roller styles. There is plenty of room inside the BMW cases for roller lifters, and they've even been offered in the aftermarket before, so I don't know what BMW's rationale was with this design. Other manufactures (Moto Guzzi) have gone this route too, so maybe there is something I am missing.

Bob
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