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  1. #1
    Duppy no who fi frighten, Make Dem Try Good2Go16's Avatar
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    Back fireing through carb's

    I have a 1200 big bore motor an its back fire through the carb's I tried tuning the carb's it still back fires I pulled the motor done to check the flywheel pin to see if I broke it an its fine but when I pulled the carb's off i notice the previous owners had 2 stock reeds an 1 aftermarket reed.

    Should I put back in a set of aftermarket reeds are stock reeds?

    Any help appriciated, by the way its a 65U block the non powervalve 1200, any advice on which reed to use would be grateful.



    I am about to use the bike for this weekends bunfire.


  2. #2
    CHICKA WAH WAH bren's Avatar
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    wow, some people hey

    replace all reeds with VF3, good quality

    some stock and some after market means some of your reeds are opening and closing at different pressure levels than others...this is not good.

  3. #3
    Moderator OsideBill's Avatar
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    On the 65U motor the stock reeds are good quality, next I would go with the Boyesson 2 stage reeds, The VF-III's do not give the same performance gain on these motors as seen on the GPR motors. Now a backfire can come from several issues like timing or an air leak. If the reed was open it would pump out air when you crank it pull the plug wires and crank it and see if this happens. Sound like you already checked the timing. Air leak would be the next thing I would look for.

  4. #4
    Moderator OsideBill's Avatar
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    I moved this to the old school section.

  5. #5
    krispaintballz's Avatar
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    Quote Originally Posted by OsideBill View Post
    On the 65U motor the stock reeds are good quality, next I would go with the Boyesson 2 stage reeds, The VF-III's do not give the same performance gain on these motors as seen on the GPR motors. Now a backfire can come from several issues like timing or an air leak. If the reed was open it would pump out air when you crank it pull the plug wires and crank it and see if this happens. Sound like you already checked the timing. Air leak would be the next thing I would look for.

    I have to disagree bill. I have used stock reeds, boyessen pro reeds, and the vf reeds. The vf reeds: two and three both out performed any reed that I used. The 3's gave me as much as 50 rpm over the Boyessen reeds. Dont get me wrong the Boyessens were good but nothing out performed the vf3's. More snap, low, and mid range pull.

  6. #6
    Duppy no who fi frighten, Make Dem Try Good2Go16's Avatar
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    Thanks guys, i checked the timing already it was good. i will try both of the aftermarket reeds then since there's mixed opinions on them.

    Thanks for letting me know you moved it Bill

  7. #7
    Moderator OsideBill's Avatar
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    Quote Originally Posted by krispaintballz View Post
    I have to disagree bill. I have used stock reeds, boyessen pro reeds, and the vf reeds. The vf reeds: two and three both out performed any reed that I used. The 3's gave me as much as 50 rpm over the Boyessen reeds. Dont get me wrong the Boyessens were good but nothing out performed the vf3's. More snap, low, and mid range pull.
    What were your results on a single pipe? IMO not worth the bucks for the singles.

  8. #8
    Duppy no who fi frighten, Make Dem Try Good2Go16's Avatar
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    +1 on that as for the bike is still running the stock exhaust just a TDR waterbox?

  9. #9
    jdog800's Avatar
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    Quote Originally Posted by OsideBill View Post
    What were your results on a single pipe? IMO not worth the bucks for the singles.
    +1 Had a set, ran them for half a season then put my stockers back on. I never saw any recordable gains when I had them nor any recordable losses when I switched back to the stock.... although I did think the mid range was slightly better.

    I almost think that lots of members buy the vf3's after they have already had some time on the old stock ones and are making comparisons with a new set of reeds compared to a set that has time on them. I would like to see someone who is running vf3's get some numbers then switch out to a brand new set of stock reeds and cages and get some numbers.... that would be a true performance gage to go by.

  10. #10
    my vfII's run the same as my 140$ carbon tech's I think the carbon techs are awesome for the price Also a reed spacer is handy on the 65u

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