Gearing Help

[8secBusa]

I need some help gearing my bike for 1/4 mile racing.
Currently I have 16/42 and cross the line at 10,500 in 4th gear. I wanted to know how much more I need to go up in the rear sprocket to go through at 10500 in 5th gear.

Thanks

Current performance 9.55 @ 143
Mods
6" extentions, Pipe, Power commander, air shifter, air box mod, lowered 3", M/T shootout tire

I am 235LBS

 

[Professor]

4th gear is a 1.286 ratio 5th gear is a 1.136 ratio

By my calculations, a 16/47 should put you very close. Most dyno sheets I have seen showing comparable bikes with your mods nosing over about 10200 or so. 16/46 should put you there about 10250rpm and might be a better choice. Might have to try both to see what works the best for you. t


Let us know. Everything about your setup, weight, etc. looks the same to me except I am running a stock arm and I'm down about 3mph from yours. I'm only down about 2"￾ ran a shootout until a couple months ago.

 

[8secBusa]

Storming Norm of MD dynoed it stock at 158, then with Orient Express full Titanium pipe with power commander adding 5 at the 80 & 100 percent throttle at 169.
Ran stock 10.09 at 137 (stock being clutch mod & strapped down).
9.91 at 141 1st mod, pipe, PC, air box mod.
9.71 at 142 with 6" extentions
9.55 at 143 with shootout tire

I did try MRX01 fuel, gained 3mph. but its such a hassle, 3 week shelf life, need to drain it after every day.