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Discussion Starter #1
so, if i want to get a baseline gearing for my xr 100 for summit, or nhis for that matter, how do i figure out what gearing i should use? lets say the limiter kicks in at 9.5 on the stock rev box. or it drops off, or whatever. (im actually running a big gun rev box, but we'll use 9.5 as a good baseline) since i cant find anyone running one, i dont know where to start. anyone got any ideas? right now its at 15front 50rear. i dont want to loose too much off the libe but 1st gear is almost useless for road racing. so should i just be looking to go down in the rear like 5 or 6? or shold i be going up int he front too? any opinions? johnny b, since youre the gearing guru?

jc

"tex, if your bikes a cheater, its not a very good one"
 

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Joe,
Pretty much the same as road racing...gonna be tough without some previous info on the track though. If the limiter kicks in halfway down the straight....well...you know you need a taller gear. If it never kicks in...that's a bit tougher cause you don't know how far from it you are, and you don't want to give away anything in grunt.

Bring a few sprockets with you if possible. I'd start with one up in the front, that's easiest way. Figure an XR has probably got the balls for about 65mph and it's probably geared for about 50 max.
JohnnyB

PS. If you know the 5th gear ratio (usually 1:1) and you know the primary gear ratio (probably around 3:1) and the rear tire OD...you can work out what ratio rear drive to use for a given mph.



Edited by - jbranson on May 17 2007 12:03:30 AM
 

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Discussion Starter #3
yeah, i figured if i could get it to 65 thatd be plenty fast on those spaghetti sticks for forks. so its just a guessing game until i can get some seat time. i dont have any real trick motor parts. 120 bbr kit. rev box. bbr pipe. and now the wheels. its not going to rev any higher, but it's got alot more umph everyplace. guess ill order 2 new fronts, and 2 new rears. sucks. i can already guess im going to have chain issues. but that should hopefully take care of it. there is only one or sometimes 2 other guys out there. the kid who wins is on a rediculous metrakit. hes easily doing 75mph id bet on the front straight.

thanks

jc

"tex, if your bikes a cheater, its not a very good one"
 

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Hey with a 120 kit..you might get 70+ mph out of it...would if it had a fairing for sure.
Sounds like fun.
JohnnyB
 

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Discussion Starter #5
thatd be alright. no tach and no speedo. makes things kinda nut as fun. ya cant figure shit out.

jc

jc

"tex, if your bikes a cheater, its not a very good one"
 
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