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Old 08-15-2010, 09:52 AM   #22 (permalink)
jackbauer
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Appreciate the vote of confidence but this is a budget conversion both in terms of money in time so i'll live with a chain. I do have an option on a bmw k75 for version 2 which is shaft drive

So I need a little advice on the sprockets. The bike's stock ratio is 2.87:1 with a 15 tooth on the engine and 43 tooth on the rear. So i've done some maths and came up with the following.
Wheel diameter : 600mm (approx)
so one turn = 1.885m
so for 1kph the wheel would turn at 8.83rpm

speed_________wheel rpm_______Motor rpm (2.87)_______Motor rpm (3.58)
50kph (30mph) = 441---------------1265-----------------------1578
100kph(60mph) = 883---------------2534-----------------------3161
145kph(90mph) = 1280--------------3673-----------------------4582

I can achieve a 3.58 ratio by keeping the stock rear sprocket and going to a 12 tooth on the motor. Bearing in mind its a twin motor setup I'm guessing i will have plenty of torque even with such a low ratio , still let the motor spin fast enough while holding them in the power band. Most bike conversion i've seen on the web have anything from 1:4 to 1:7 ratios but most are using agni or perm motors. Any advice much appreciated.
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Now, Cole, when you shift the gear and that little needle on the ammeter goes into the red and reads 2000 Amps, that's bad.
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