JACKSHAFT is the way......My setup engine is 19 at the clutch to 57 (this a Buller Belt drive) over to 21 and at the axle 53 (the last 2 are 35 chain and sprockets) so to get more torque I change the 21 to an 18 more speed 21 to 23. Either way by changing just one sprocket the gear ratio can be changed in minutes with little work. My approach is a little different. My banshee I wanted Top rpm at 3/4 of the way thru the longest straightaway....otherwise the motor tops out and runs it's lungs out for nothing. I started with a 3 to one ratio on the clutch to jackshaft pulley that part I will never change. So with two gears left I got for the axel a 60,58,55,53.....for the jackshaft output I got 15,17,18,19,20,21,22....First test I went 60-18.....way to slow but eventually working from back to front I got where I am ........ Now I know how the kart reacts on short runs verses long runs. Once you get to know how your engine works with certain gears you can make a formula for example mine is top engine rpm = 14,500 divided by final drive ratio=7.85 = 1847.13 that number is wheel rotations per minute flat out I mutiply that number by my tire diameter = 34.5 inches which gives me inches per hour divided by 12 = feet per hour divided by 5280 = my top speed at top rpm with that ratio. Hope that helps kind of my backwards way of doing it.
RR
