Airhead oil change, what up with the scare on the white o ring?

Discussion in 'Airheads' started by Sniper X, Sep 29, 2010.

  1. Sniper X

    Sniper X De Oppresso Liber

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    Fill me in as I am about to do one on my R100RS with a new filter and premium oil. Can I use Mobile 1 or some total synthetic or should I even bother?
    #1
  2. Mista Vern

    Mista Vern Knows all - tells some.

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    Look it up on Snowbum's site I sent ya - lots on the expensive O ring there. If you start running synthetic you may find that the bike starts to leak past various seals. A lot of guys run Rotella, as it contains higher zinc and other elements that protect the engine better than car oils do, plus it is cheap.
    #2
  3. Renner

    Renner combustophile

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    excellent write-up on the o-ring at Anton's site: http://www.largiader.com/tech/filters/
    be sure to click on the linked words on that page.

    too much fear & loathing over a task which requires some thought & finesse
    #3
  4. Bill Harris

    Bill Harris Confirmed Curmudgeon

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    Anton's O-ring writeup is excellent.

    The "$2000 O-ring" may be much to do about nothing once you understand it, but a lot of people have bought a lot of expensive work over that Airhead quirk... :huh
    #4
  5. dduelin

    dduelin Be Thou My Vision, Oh Lord Of My Heart

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    I am not going to touch the "what oil" to use but I will share my reasoning for not running synthetics in my airhead. I do run API rating SG or SH 20w-50 oils for their higher concentrations of zinc which have been lowered in newer SL or SM rated oils. I change the oil at 2000 to 3000 miles and I believe there is little degradation of dino oil qualities in this short time to offset the higher cost of synthetics.
    #5
  6. Sniper X

    Sniper X De Oppresso Liber

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    Looks like a little common sense realy, plsu, since I am already running Rotella T I will continue to do so.

    thanks!!!

    Kevin
    #6
  7. ashrubbery

    ashrubbery Adventurer

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    mmm, im also not really sure about that O ring too. A mechanic I know has owned bmw airheads for decades, and hes never worried about the O ring, hes reguarily mantained his bikes and nothings really given him any trouble, no $2,000 rebuild... he doesnt quite get what the fuss is all about. Anyway, I changed my oil, and it turns out that the metal shim was all bent and messed up and was cutting that white O ring. Well, after discussing it and what not, I got a new O ring, threw away the metal shim, and well, didnt use a metal shim at all i dont think, when putting it back... Smeared a good amount of gasketting glue on all around there if I remember correctly. i dont really have the knowledge about bikes, or anything mechanical to disagree with someone whos been doing it the same way for all these years and not having experienced a problem... just hoping it will be ok!

    im not disagreeing or anything, just telling a story
    #7
  8. P B G

    P B G Long timer

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    Anton's write up is clearer and has good diagrams.

    This O ring thing is simple.

    There are two types of canister, one w/ a rounded lip, and one w/ an unfinished/not rounded lip. If your bike's is rounded you only need shims if the measurement to that surface is too deep.

    If its not rounded you need atleast 1 shim.

    How many shims you need is a function of the measurement. Each shim is a certain thickness, and you're aiming for a certain range of o-ring compression.

    There is a chart on his page, http://www.largiader.com/tech/filters/canister.html

    The place where some people cause trouble, is that they will put in 1 shim and 1 gasket. As this is what the kit comes with. That gasket can prevent oil from leaking from the engine, but it will reduce o-ring compression, so in theory if your o-ring isn't compressed and you have a gasket there, your engine can be pushing the oil past the o-ring and therefore not having enough pressure to circulate it where it needs to go, even though the yellow light is not on. If you don't have the gasket, and the o-ring is leaking it will weap around the cover.

    It is not at all scary, and I would wager most airheads w/ no cover gasket, 1 shim, and the o-ring are safe. So as long as your mechanic tosses that gasket in the trash, installs the 1 shim and bolts it up, the engine will probably do fine.

    Personally I'm running 3 shims in mine, no gasket, measurement of depth yields 4.1mm, 3 shims compresses the o-ring to about 3.2, which gives me a warm feeling because I don't feel undercompressed. When I first got the bike however it had 1 shim and a slight weaping from around the cover. The o-ring was rather round when I removed it.
    #8
  9. Uncle Pollo

    Uncle Pollo Bad Hombre

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    Oh fucke ... where do I get the shims?
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  10. P B G

    P B G Long timer

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    Come w/ oil filter kit, reusable.
    #10
  11. bmwhacker

    bmwhacker Still on 3 wheels

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    My non leaking "well broke in" (50k miles) R75/5 sprung 3 different leaks within 100 miles after going to semi-synthetic oil. Rebuilt top end ( up to 900cc), all gaskets and seals...no more synthetic blend oils for me....
    #11
  12. boxerboy81

    boxerboy81 Stay Horizontal

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    Whilst you're in there, check the $2000 oil bypass spring too.
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  13. Steptoe

    Steptoe steptoe

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    Pity you then proceed to complicate it even further with your reply :D
    #13