Valve noise.....

Discussion in 'Airheads' started by super-single, Apr 24, 2012.

  1. super-single

    super-single Been here awhile

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    Got the 93 r100gs on the road a bit and like it.....New fork bushings , swing arm bearings , steering head bearings and
    more . She drives nice but makes a lot of noise on the RH side . Valve clearance is at .004 on the intake and .006 on the
    exhaust . There seems to be a lot of end play in the exhaust rocker though - about a .005 gap . Anybody shimmed ?
    #1
  2. supershaft

    supershaft because I can

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    I don't think a lot of people realize it but you can adjust rocker arm end play on the later shimmed setups just like you do on the earlier setups. There is still a lot of give there. I rarely ever change shims.

    All things being equal, the right side is noisier because it is closer to your ear. Keep that in mind. Move your head and your knees around and you should get my point real quick.
    #2
  3. super-single

    super-single Been here awhile

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    Thanks . Both of the left rockers have minimal play and really are quieter . Thanks for the tip though . This is my first newer
    air head and I didn't realize the rocker blocks were sleeve located till I read up on it . The post also emphasized the importance of centering of the pushrod . The pushrod on the sloppy rocker appears to be on the high side so I am wondering if pulling the blocks closer together will be as good as shimming from the top side of the rocker ???
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  4. supershaft

    supershaft because I can

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    I look more at centering the rocker on the valve tip myself. Unless something is quite a bit off. I loosen the bottom nut to make adjustments. The bottom studs have way more thread purchase and are consequently way less likely to pull threads. I think using an old CC products style modified C clamp Vise Grip is THE best way to adjust rocker arm play down to a gnat's ass. In my experience, a fine frog hair does make a difference there.
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  5. super-single

    super-single Been here awhile

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    Cool , thanks I'll look it over .............
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  6. fishkens

    fishkens Long timer

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    On the flipside, if you're taking the valve train off it doesn't hurt to buy an assortment of shims, measure the clearances and re-sort shims to close up the gaps and then finish it as SS describes. I've done this twice (maybe three times) over the life of my GS and it's helped keep it quiet. Both approaches can work. .005 is getting is near the size of the thin shim.

    p.s. Ooh, I guess I should sign this super-fishkens :lol3
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  7. super-single

    super-single Been here awhile

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    Super fishkens , thanks for the input . That was one of the things I was most curious about .
    The stacking of shims being an acceptable practice if necessary ......
    Oh by the way , my super -single is the Yamaha SRX-6 !!8^)
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  8. Kai Ju

    Kai Ju Long timer

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    SRX-6 is one of my all time favorite bikes. Yamaha really did it right with that one but in typical fashion it didn't sell well here in the US. The average American rider will not suffer a kickstart single. Don't know what they're missing.
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  9. supershaft

    supershaft because I can

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    Sure! Stacking shims is OK. I am guessing you just about have to sometimes?

    Re-stacking shims? They almost always stay right where I adjust them to in my experience. Even for a lot of miles.
    #9
  10. DoktorT

    DoktorT BigBrowedNeandereer

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    Well, that's just dead wrong. The rocker should be just off center to insure rotation of the valve to maintain seat and valve concentricity during operation.

    Tons of garbage advise can never trump this.
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  11. supershaft

    supershaft because I can

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    I don't think you have to worry about the valve rotating. They very often look perfectly centered to me and they still rotate. I don't think you can get them to not rotate without modifying the keepers but I have seen quite few rocker arm tips get off to the side enough that it wears the rocker arm radius excessively on the part that touches the valve tip and none at all on the rest of the radius. It makes for a messed up rocker arm that needs replacing.
    #11
  12. pommie john

    pommie john Long timer

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    To be honest, I don't see how you can make a valve rotate just by offsetting the rocker arm by a couple of mm. The valve is clamped tightly to the collets which are tight on the keeper, which is held by a fair bit of spring pressure to the spring and then on to the head.
    can it really make a difference if the rocker arm is offset by a tiny amount.
    I'm very sceptical of that.

    There are plenty of engines from American V8s to Italian supercars that use roller rockers and they can't possibly spin the valves and they don't seem to suffer valve wear more than any other engine. It sounds like car club hocus pocus to me.
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  13. robtg

    robtg Been here awhile

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    Actually the collets butt together before they get a grip on the valve and allow the valve rotate. To center the rocker over the valve with enough precision to keep the valve from rotating would be next to impossible.
    SS is correct and DrT is dead wrong.
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  14. pommie john

    pommie john Long timer

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    Hmm. OK. I must confess that I've not looked that closely at the BMW collets, but certainly on my Norton, the collets grip the valve, there's definitely a gap between them so they must be hard up against the valve stem.
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  15. supershaft

    supershaft because I can

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    Thanks robtg! From what I have seen I think it would be next to impossible too.

    As I understand it pj, very few motorcycle engines have rotating valves excepting BMW's although it is pretty common at least in American cars. So far that adds up with what I have noticed.
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  16. Bigger Al

    Bigger Al Still a stupid tire guy

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    Imagine that. :1drink
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  17. Stagehand

    Stagehand Imperfectionist

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    Interesting tidbits in this thread. I will say that I dont know if I'd measure .005 I just know its supposed to be none for all practical purposes. Just an oil film showing, but smooth action and no binding.

    Curious note about the cylinder studs being centered... That actually might explain a little bit... :eyes

    and about loosening the bottom bolt..

    no info on the centering of the rocker tip on the valve, I figured they were designed to hit it right if I got the thing bolted up right and shimmed. Never even thought about it.

    but apart from that, I reshimmed kind of recently. Why is the .035 the only one thats $3 while all the others are $0.25? I'm laughing, but its a serious question.
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  18. super-single

    super-single Been here awhile

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    Ladies and Gentlemen , thanks for sharing in on this thread , I must apologize though .
    When I started this thread I used the figure of .005 , but I foregot to specify that this figure is in
    inches , that puts the metric measurement at .127.......some of you may say , "So , why do
    you want to monkey with this?" In the future , I will try to specify the inches or millimeters.
    Remember though , The decimal point location is critical !!8^)
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  19. supershaft

    supershaft because I can

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    IMO, .005" is plenty more than enough to cause noise if you listen close enough. I run them a lot tighter than that but not too tight! That's where a modified Vise Grip is real handy. Good luck!
    #19
  20. fishkens

    fishkens Long timer

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    Yep, I assumed .005" which is plenty of gap to create a rattle - esp. when I try to close end play down to virtually nothing (as Stagehand suggests).

    So, given that the thinnest shim BMW sells is .2 mm, the .127mm can be closed up by replacing (restacking), for example, two .2mm shims with a .2mm and .3mm shim. This would reduce the .127mm to .027mm which can be closed up with tightening and would probably quiet the valve train quite a bit.

    Make sense?
    #20