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  1. #1
    Big K's son KeithKman's Avatar
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    RIVA Reduction Nozzle RPM question...

    Say you are running a 83mm ring and jump down to a 82mm or 81mm ring. Per 1mm, what is the effect on RPM?


  2. #2
    West Texas RXP skoepp's Avatar
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    I have read were guys see 80 - 100 rpm difference.
    At my altitude it is only 50 to 60 rpm.
    that is for 1 mm ring change.

  3. #3
    Big K's son KeithKman's Avatar
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    You are at 500 feet above sea-level, right?

  4. #4
    West Texas RXP skoepp's Avatar
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    Quote Originally Posted by KeithKman View Post
    You are at 500 feet above sea-level, right?

    I wish.
    I ride at anywhere between 2,200 to 3,500 ft. Then factor in heat and pressure and my corrected elevation is anywhere between 4,500 to 5,800 ft.
    I love the winter months.

  5. #5
    DaveC's Avatar
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    I usually see 40-60 RPM difference in changing the venturi rings.

  6. #6
    Big K's son KeithKman's Avatar
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    Quote Originally Posted by skoepp View Post
    I wish.
    I ride at anywhere between 2,200 to 3,500 ft. Then factor in heat and pressure and my corrected elevation is anywhere between 4,500 to 5,800 ft.
    I love the winter months.
    Same here. Where I ride, the elevation is 1,104 above sea level. Factor in the 4% humidity, 115 degree air, with the 87 degree water and it's like riding at 3,000 to 4,000 above sea level.


    Quote Originally Posted by DaveC View Post
    I usually see 40-60 RPM difference in changing the venturi rings.
    Cool!

  7. #7

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    Another way to put it. . . if you go from stock (83.5 mm) down to 81 mm and add enough power to keep the rpm the same, you gain right at 2 mph.

  8. #8
    Big K's son KeithKman's Avatar
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    Quote Originally Posted by engineermike View Post
    Another way to put it. . . if you go from stock (83.5 mm) down to 81 mm and add enough power to keep the rpm the same, you gain right at 2 mph.
    I think I'll end up buying a 84 and 85 ring. In the summer it gets really hot.

  9. #9
    TheXrider's Avatar
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    what size would the riva reduction nozzle be without a ring? and can it be runned with out the ring?

  10. #10

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    88mm without a ring, though much of the venturi is the same size as OEM. Probably not the same as being bored out 88mm all the way. You can run without a ring, but the effectiveness is uncertain.

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