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Sportster Motorcycle Drag Racing Discuss drag racing on a Sportster Motorcycle.

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  #11  
Old 2 Days Ago
Hightop Hightop is offline
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Originally Posted by conv90 View Post
very short forks , very short shocks , 6000 rpm and dumb the clutch and stock tires, advanced position seat? Is this the recipe to not flip the bike while letting the clutch lever? With my sportster if I let the clutch like this, I can't avoid tipping over..
When you use short rear shocks, the swingarm pivot is much lower than the center of gravity, all your power is pushing here, forcing the front up. Better to use shocks resulting in a level swingarm angle, IMO

If you tie the front end down instead of lowering it, you force the bike to raise the weight from the lower legs, brakes, and wheel and tire right from the hit, making a wheelie more difficult. If it's just lowered, you'll get an inch or so of extension before making it do the heavy lifting, and it's already moving in that direction, kind of like it's easier to wheelie if you pull back on the bars when you crack the throttle to get it moving
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  #12  
Old 1 Day Ago
Tomcatt Tomcatt is offline
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Originally Posted by conv90 View Post
very short forks , very short shocks , 6000 rpm and dumb the clutch and stock tires, advanced position seat? Is this the recipe to not flip the bike while letting the clutch lever? With my sportster if I let the clutch like this, I can't avoid tipping over..
Don't "dump the clutch". Slip the clutch to control wheelspin / wheelies. Adjust your launch rpm so you can pretty much hold the throttle wide open thru first gear while slipping the clutch.
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  #13  
Old 13 Hours Ago
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conv90 conv90 is offline
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Originally Posted by Hightop View Post
When you use short rear shocks, the swingarm pivot is much lower than the center of gravity, all your power is pushing here, forcing the front up. Better to use shocks resulting in a level swingarm angle, IMO

If you tie the front end down instead of lowering it, you force the bike to raise the weight from the lower legs, brakes, and wheel and tire right from the hit, making a wheelie more difficult. If it's just lowered, you'll get an inch or so of extension before making it do the heavy lifting, and it's already moving in that direction, kind of like it's easier to wheelie if you pull back on the bars when you crack the throttle to get it moving
Correct. I see now the video that alla are with front tied.
About the rear it seems they are all with very short shock with the pivot point of the swingarm slightly lower that the center of the wheel (probably almost rigid like ).
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  #14  
Old 13 Hours Ago
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conv90 conv90 is offline
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Quote:
Originally Posted by Tomcatt View Post
Don't "dump the clutch". Slip the clutch to control wheelspin / wheelies. Adjust your launch rpm so you can pretty much hold the throttle wide open thru first gear while slipping the clutch.
I was referring to the video. It seems they are all skilled guys.
They dump the clutch, you can see for example the second pass of the guy in the left lane letting the lever during start.
There is no squat , the bikes seems rigid.
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