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Thread: Looking for Technical Advice

  1. #1
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    Looking for Technical Advice

    What would need to be done to a bone stock XB12 STT engine to have it run for up to 36 hours near the higher rev limit?

  2. #2
    Senior Member Cooter's Avatar
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    "The answers you want, can only be as good as the questions you ask"

    But I'm bored, so I'll guess!

    The problem isn't RPM, these will run under redline until Mike Lowreys handlebar clamps wear out. The problem is load, asking an engine to make high HP for long times builds heat.

    Running it in the bike for something like the iron-butt nonsense? Sure, I'd do that. Theres much better choices, but I get thats not the point, LOL. The BSFC on a Buell has got to be terrible!
    On a road course like a 36 hours of Le-Mans thing? Maybe not.
    Hooked up to a pump or generator at full load? NO.

    Marine engines live that life, look at what they do, like bearing seats for the valve springs, and you'll know why marine engines are so dang expensive.

    Good luck, I'd like to hear more of this mystery question

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    Member Barrett's Avatar
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    Quote Originally Posted by Johnnie View Post
    What would need to be done to a bone stock XB12 STT engine to have it run for up to 36 hours near the higher rev limit?

    nothing. NO XB motor will ever live at or near redline for even a few hours...let alone 36.
    why? the inherent design. which is what? fork-and-knife-style con rod big ends sharing a common pin and roller bearing.
    how do i know? the XBRR racing series. though this model was consistently revved to between 8500-9000rpm...and it's crank and stroke dimensions were XB9 based for theoretical longer bottom-end life....each motor was considered "used up" and requiring a tear-down and full rebuild around the 7-9 hour mark.

    next question: i'm considering purchasing a beautiful low mileage one owner Harley-Davidson XR1200 that i stumbled upon. would it make a good arena-cross ride that i can back-flip on a consistent basis?

    yes sir, it indeed would. i flip mine at least once every other ride.


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    Lmao

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    Think sea to shining sea - current record set in 2019 is 37 hours 7 minutes @ an average of 75mph. I think it can be done on a southerly route at around 80-85 mph in mid spring. The last two record passes were set by a Yamaha Super Ténéré and a BMW K 1600 GT. I would like to see it set on an American production bike.To do this you will have to have several (many) long periods of time at or around 100 mph for several hours. Will the motor hold up? Through the process of elimination I have arrived at using a Buell versus a Motus - with modifications to strengthen the engine.

  6. #6
    Senior Member 34nineteen's Avatar
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    Quote Originally Posted by Johnnie View Post
    Think sea to shining sea - current record set in 2019 is 37 hours 7 minutes @ an average of 75mph. I think it can be done on a southerly route at around 80-85 mph in mid spring. The last two record passes were set by a Yamaha Super Ténéré and a BMW K 1600 GT. I would like to see it set on an American production bike.To do this you will have to have several (many) long periods of time at or around 100 mph for several hours. Will the motor hold up? Through the process of elimination I have arrived at using a Buell versus a Motus - with modifications to strengthen the engine.
    No offense, but why would you want to take a wonderful trip like that and try to get it done soon as possible? That sounds like a trip that should take about a month, full of rest stops, greasy spoons, photo ops, etc.

    Why not take an American production bike that was designed to do the task at hand? Like a Harley bagger.

    It would be something else altogether, if Buell was still in existence and you wanted to collaborate with the factory to show that this is another one of the perks of owning a Buell. Court Canfield did that back in the day and it seemed like a great thing. But, hey... you do you.



  7. #7
    Senior Member Cooter's Avatar
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    Quote Originally Posted by Cooter View Post
    Running it in the bike for something like the iron-butt nonsense? Sure, I'd do that. Theres much better choices,
    Called it...

  8. #8
    Senior Member rb70383's Avatar
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    They have a cannonball run for bikes!?! Hmmm
    Only engines I know designed to run loaded for hours on end, don't have spark plugs...
    I would love to do a balls to the wall cross country low flying trip. And then the relaxed gawk at everything on the way back. Or maybe the easy leg first, then fly to get home....

    That said How would these engines hold up to pretty much a constant rpm at higher load levels? On the track, loads are great but not continuous

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    Senior Member Cooter's Avatar
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    I'm dumb but I honestly think a stock Buell engine would survive below stock redline. I don't think the load at a constant 100mph is that big? Shoot for the least weight and wind resistance you can, yell "hold my beer!" and let us know if you survive

    They have enough power to run a lower RPM and gearing will be VERY important, since I know of no way to get a 6 speed in the XB cases, use a tuber engine and add a 6 speed. 100mph is pretty comfy on a yellow, 6-speed M-2, through Idaho, for very long distances, with Optomist (Alledgedly).

    An S3T with gas cans in the bags would fit the bill Make sure to have a full belly pan fabbed because if it goes, it will be catastrophic.

    Talk to a true Buell engine builder, and see what they say? I think Barrett has a really good point about the con rods sharing a bearing journal being a weak point, but get the RPM to 5k-ish at stock power levels and maybe survive? The right/good oil will be very, very important.

    As a side note, this seems fun but VERY ambitious. Do yourself a favor and spend some time with a calculator. A nationwide speed average of 75mph takes a whole lot more than some speed blasting at 100 mph through Kansas.

    Engine tech:
    http://nrhsperformance.com
    Transmission tech:
    http://www.rd-motorsports.com
    Smart people to ask:
    https://www.ironbutt.org
    You'll be needing this:
    https://www.online-calculator.com


    Last edited by Cooter; 06-24-2020 at 06:19 PM.

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