Hi
have a problem, my kr1s is reving at 11000 revs in top but only pulling 120mph with standard gearing does anyone know how i can identify if i have a close ratio gear box installed
cheers
rick
KR1S close ratio gearbox??
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KR-1R
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60xRPM * [Primary reduction (24/61) * gear ratio * Final drive (14/41)] * tyre circumference(/1000)
^^^ the speed equation has THREE user changeable VARIABLES (the primary reduct is a constant = pinion to clutch basket)
on paper there is a 20% difference in 6th gear on the 'R' (D) over a B or C model This difference is slightly less because the R has slightly taller final drive ratio
however there multiple other factors, all adding to overall differences between ideal calculated, and actual top speed...
1... speedo error (are you really doing 120) probably up to +5%
2... tacho error (normally higher than actual, could be up to +10%)
3... clutch slippage 0%- 100% (but you will probably know theres something really amiss if this is anywhere over 20%) you will see this in higher gears, and speeds and wind resistance
4... what is standard gearing 15/40, 15/41, 14/41 <<< all standard depending on market... another +/-10% difference (or more with 13 front sprocket combos)
5... the profile/height of your rear tyre standard width/height? also profile change due to fling/growth at speed - (up to +/-5% just changing tyre brand/model)
eg. (1) + (4) = 15%
CHECK you have sufficient free-play in your clutch cable
you can determine if you have a close ratio R box, by the gear ratio of your 6th cog...
BY HAND, manually turn over the motor over in top gear and count the splines on the gearbox output shaft (this will eliminate the major clutch slip factor) - count the output shaft rotations versus crankshaft turns
^^^ the speed equation has THREE user changeable VARIABLES (the primary reduct is a constant = pinion to clutch basket)
on paper there is a 20% difference in 6th gear on the 'R' (D) over a B or C model This difference is slightly less because the R has slightly taller final drive ratio
however there multiple other factors, all adding to overall differences between ideal calculated, and actual top speed...
1... speedo error (are you really doing 120) probably up to +5%
2... tacho error (normally higher than actual, could be up to +10%)
3... clutch slippage 0%- 100% (but you will probably know theres something really amiss if this is anywhere over 20%) you will see this in higher gears, and speeds and wind resistance
4... what is standard gearing 15/40, 15/41, 14/41 <<< all standard depending on market... another +/-10% difference (or more with 13 front sprocket combos)
5... the profile/height of your rear tyre standard width/height? also profile change due to fling/growth at speed - (up to +/-5% just changing tyre brand/model)
eg. (1) + (4) = 15%
CHECK you have sufficient free-play in your clutch cable
you can determine if you have a close ratio R box, by the gear ratio of your 6th cog...
BY HAND, manually turn over the motor over in top gear and count the splines on the gearbox output shaft (this will eliminate the major clutch slip factor) - count the output shaft rotations versus crankshaft turns
Last edited by KR-1R on Mon Oct 29, 2012 10:04 am, edited 3 times in total.
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rickychutney
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