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Thread: Race Buell Improvement Thread

  1. #41
    Senior Member Kurlon's Avatar
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    Stock motor, my XB12XT won't pull to redline in 5th, seems to be good for 131mph-ish, 6400RPM on top. Current gearing is 27/65, I see Evol Industries makes a 26t front as well as stock 27t... would I be able to get away with that with the stock belt to squeeze a hair more out of the Uly on top?

  2. #42
    Senior Member Barrett's Avatar
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    Quote Originally Posted by Kurlon View Post
    Stock motor, my XB12XT won't pull to redline in 5th, seems to be good for 131mph-ish, 6400RPM on top. Current gearing is 27/65, I see Evol Industries makes a 26t front as well as stock 27t... would I be able to get away with that with the stock belt to squeeze a hair more out of the Uly on top?


    would I be able to get away with that with the stock belt

    NO

  3. #43
    Senior Member Kurlon's Avatar
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    Right, so chain drive conversion sooner rather than later, and decide how deep into a motor build I'm going to go for the second half of the season. Was really hoping with all the talk of relaxing the tension on stock setups that there'd be some wiggle room, but guess not, bah. I'm adding "Barrett said I couldn't" to my big book of excuses.

  4. #44
    Senior Member 34nineteen's Avatar
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    You may be able to find a XB9 front primary sprocket (and chain) to get some more reduction. That's on my list of things to do. You will need to find a 08-10 sprocket only that is held on by a bolt (not a nut).

    I could have sworn there was a Euro-spec pulley/belt setup with different ratios, but that may have been for the tubers only.


    Above all, WWBD (what would Barrett do).
    Last edited by 34nineteen; 03-01-2024 at 02:00 AM.

  5. #45
    Senior Member Kurlon's Avatar
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    Found half a unicorn... now to find the other half.

  6. #46
    Senior Member Kurlon's Avatar
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    Chain drive will be the likely end game, along with breathing on the motor. Short term, I believe the full XB9 primary gearing swap would be too short and I'd be capping my top speed below where it's at now. It looks like I *can* source different length primary chains so there is room to chase things there as Evo Indus has a pretty wide range of primary sprockets to go shorter incrementally, and a 56T basket to go slightly taller while leaving the belt drive alone. That's worth exploring I think as a chain drive conversion, done right is NOT cheap, and I want to go aluminum primary anyways.

  7. #47
    Senior Member Cooter's Avatar
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    Never had a problem with a chain conversion done cheap. Thats my middle name!

    Even on a few very hopped up 12's. I could absolutely tell a difference between the belt and a chain on initial throttle. Not having any belt stretch or cush drive made a noticeable difference. Kept a real close eye on the rear hub/bolts, and the nylon idler and didn't have rapid wear or loosening/cracking of the wheel

  8. #48
    Senior Member 34nineteen's Avatar
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    After a lovely sushi dinner with CoOter, it was pointed out to me that I may not be the best source of advice for race/track bike gearing.

  9. #49
    Senior Member Cooter's Avatar
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    I may not be either! I'm just a copy cat to what successful teams do. Way to dumb to think of this stuff on my own

    And Sushi was great!

  10. #50
    Senior Member Kurlon's Avatar
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    And... this project is done. I was 13 seconds out of the qualifying cutoff in Q1, with a trap speed of 136.8mph vs 169mph, 5 more laps in Q2 wasn't going to magically close either of those gaps so I've packed up and am on my way home, the MotoAmerica shenanigans are done now. MA is strictly enforcing the qualifying cutoff for the class, and with the removal of the American AirCooled Twins subclass, the only two aircooled machines that entered that I know of were myself and a crazy built Polaris Victory in a custom frame that was having major running issues so also didn't qual. All of the Sportsters, Big Twins, etc from last year didn't show up, looks like there were maybe half as many entries as we had at COTA? Maybe they skipped Daytona on purpose and will show up at other tracks, but they'll have to meet the same 115% time of the Indians as everyone else.



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