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  1. #1
    Budman's Avatar
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    Are factory carb settings ok after modifying engine?

    Here is a list of the engine mods I have made on my 98 GP1200.
    Cylinders ported for 92 octane pump gas.
    Factory head milled by riva motorsports.
    Riva flame arrestors.
    Riva return line restrictor with 105 jet.
    R&D reed stuffers.
    Premix with 40:1 amsoil interceptor.
    Will this setup work with the carbs still original or do I need to rejet? The carbs were rebuilt last year by a yamaha dealer.

    Thanks


  2. #2
    Moderated
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    rejet.

  3. #3
    Yamaha artisan Cutlass's Avatar
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    agree. Rejet

  4. #4
    Budman's Avatar
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    Is it just a power issue or will it damage the engine if I didn't rejet? Do the carbs need to be rebuilt again to change the jets? Also what size jets would work best?
    Thanks

  5. #5

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    Will run too lean. Rejet

  6. #6
    Yamaha artisan Cutlass's Avatar
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    yes. It'll run too lean and damage the engine. Who ported your cylinders? They might have a suggestion on jets.

  7. #7
    Budman's Avatar
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    The porting is being done by Tim Judge.

  8. #8
    Budman's Avatar
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    Is it just a matter of putting in new jets or do I have to change the mixture screws? Can the carbs be opened up without replacing the seals?

  9. #9
    Yamaha artisan Cutlass's Avatar
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    Quote Originally Posted by Budman View Post
    Is it just a matter of putting in new jets or do I have to change the mixture screws? Can the carbs be opened up without replacing the seals?
    Its good practice to replace carb gaskets and seals when you open up the carbs. That being said, if you think the seals and gasket are in good condition when you open them up, you can reuse them. But be cautious. This is your motor on the line if you guess wrong.
    IMHO...I'd use new gaskets and seals.

    And yes you will need to change the mixture screws. Everything about the engine is different now. You'll have to adjust the low speed screws, pop off pressure, low speed jets, high speed jet, and high speed adjuster. Luckily this has all been done before, so you should be able to find what worked for others and yours should be very close to that.

  10. #10
    Budman's Avatar
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    I'm sure glade I asked these questions. I was going to just put the carbs back on and go. Thanks for all the help. It probably saved me an engine. I think I will send osidebill an email get a quote. I've put a lot of money in these mods and I don't want to screw it up.

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