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Hello All,

I've been reading about how to calculate your IPR (inch per revolution), and I was wondering if you could easily match the needed ratio to get a 4 cycle to perform similar to a 2 cycle in terms of IPR. The formula I came across is;

Rear Tire Circumference (R) X Engine procket (E) divided by Axle Sprocket (A), thus   R x E
                                                                                                                              A


If I'm running a 2 cycle road course kart with a 10 tooth engine sprocket, 86 tooth axle sprocket, and rear tire circumference of 35", the formula would look like this;

     35 X 10 = 4.06 inches per engine revolution, or 4.06 IPR
         86


My son is running a 4 cycle road course kart with a 18 tooth engine sprocket, 58 tooth axle sprocket, and rear tire circumference of 34.5", the formula would look like this;

     34.5 X 18 = 10.7 IPR
         58

On paper, that looks like he's running twice as fast as I am, but that's not true (is it?)

All comments welcome!