Yamaha R3 tuning q's
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Yamaha R3 tuning q's

This is a discussion on Yamaha R3 tuning q's within the Technical forums, part of the Caferacer.net Forums category; Any 2-smoke guys out there? I have a co-worker who is trying to get his 1969 Yamaha R3 running right. It has open pipes and ...

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  1. #1
    copperhead's Avatar
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    Yamaha R3 tuning q's

    Any 2-smoke guys out there? I have a co-worker who is trying to get his 1969 Yamaha R3 running right. It has open pipes and pod filters. We set it up on the Dyno this evening, and is running WAY lean. Anyone run one of these have any experience with jetting on these?

    Thanks,

    Eric





    Edited by - copperhead on Jun 20 2007 10:24:25 PM

  2. #2
    Senior Member kenessex's Avatar
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    Bigger main jets.

    Ken

    AHRMA 412
    Vintage racing - old guys on old bikes

  3. #3
    Senior Member Geeto67's Avatar
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    open pipes as in stock pipes missing silencers or a set of stinger pipes without silencers? If they are stock pipes for god's sake put the baffle back in.

    Do the pods have metal tops? Pod filters on a street two stroke are generally a bad idea. The metal tops can create reversion just like the chambers do so instead of forcing a fuel charge back into the combustion chamber you are forcing one into the exhaust. Try putting a piece of dense foam inside the air cleaner top and see if that helps.


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  5. #4
    Moderator joe c's Avatar
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    quote:
    open pipes as in stock pipes missing silencers or a set of stinger pipes without silencers? If they are stock pipes for god's sake put the baffle back in.
    not that was funny

    jc






  6. #5
    copperhead's Avatar
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    quotepen pipes as in stock pipes missing silencers or a set of stinger pipes without silencers? If they are stock pipes for god's sake put the baffle back in.
    Sorry, These are Stock chrome pipes that seem to have lost any internal baffeling. He purchased the bike this way and does not have the stock components.

    I think after speaking with one of the techs that used to race a 2-stroke sled, he is going to try to find some stock components and go from there. That or at least find someone who has experience with exhaust and performance combos for them, and to source something. He really wants to cafe the bike, but needs to get it running properly first. It will fire up and idle OK, but at 1/3 throttle and up it leans WAY out. The bike also seems to intermittently cut out on each cylinder so there may be some other problems in the mix.

    It's his first vintage bike, plus it's a 2 stroke, so there is a large learning curve. My experience is mainly with older German and British 4 strokes. I told him about this place, and hope he can log on and check things out.


    Thanks again



  7. #6
    Senior Member Geeto67's Avatar
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    sounds like the ignition timing is way out if it is leaning out as you speed the engine up.

    I am not that familar with the R3, but all other two strokes I have owned have two timing marks, one for each cylinder and you time them like two singles stuck together. You may want to consult the manual and then check to see that each cylinder is set to the correct timing mark and that the points are opening properly. Put a timing light on it while running and see where it moves. Improper timing may also be why it is cutting out.

    A lot of stock two strokes use the internal silencers and baffles as reversion cones, without them the bike won't run right.

    Edited by - geeto67 on Jun 22 2007 10:55:56 AM

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