This converter requires the use of Javascript enabled and capable browsers. The purpose of this calculator is to determine the potential speed of a go kart based on certain data. Enter the diameter of the drive (power) wheel and tire combination. (Make sure the tire is properly inflated and in good condition.) The diameter is the radius * 2, or in this case, twice the distance from the ground to the center of the axle. Enter the published maximum rated sustainable RPM for the engine you are using. Standard "lawnmower" engines might be as few as 2400 and high performance engines as high as 9000 RPM. The majority are from 3000 to 4000 RPM. Enter the number of teeth or sprocket splines on the axle (higher number, probably 50 to 70) and on the clutch or engine (smaller number, probably 8 to 15). The ratio of those numbers yields the best power (faster acceleration) or the best high end speed, or a compromise of both. The higher the gear ratio, the higher the top end speed; the lower the ratio, the stronger the acceleration (power). Click on Calculate. The results are the circumference of the drive wheel/tire combo (in inches), gear ratio and the potential maximum speed (in MPH). Our default is for a slow, safe junior kart. The gear ratio is 5 and the potential speed is just under 13 miles per hour. You might also enjoy visiting First Kart, an excellent site for karting fans. Another karting calculator is also in metric.
Applicable Calculator Formulae
PI = 3.14159
PI * D = C (3.14159 * wheel/tire diameter = circumference of wheel and tire combo)
at / ct = GR (gear ratio = axle teeth / clutch or engine teeth)
RPM / GR = WRPM (engine RPM / gear ration = Wheel RPM)
C / 12 = Cf (circumference of wheel/tire combo in feet = circumference / 12 inches)
FPM = Cf * WRPM (wheel RPM * circumference in feet = feet per minute)
FPM * 60 = FPH (feet per minute * 60 minutes = feet per hour)
FPH / 5280 = MPH (feet per hour / 5280 feet = miles per hour)