sprocket question

[minimoto18]

Well I have ths go kart its a carter go kart and the torque converter went to crap both the drive and secondary are junk. So I am converting it to a jack shaft. It has a 14 tooth clutch and I don't know what size sprocket to do where the old secondary was. Then it goes to a 12 tooth to a 60 at the tire what size sprocket would be the one to put in that spot to make it go about 30 to 40 mph....? I've tried using websites but they only tell me gear ratio and i don't know how to convert that to speed

 

[TANKSAREUS]

On google, seach for gear ratio, should be a thread under diy carts, its quite cool, if not search at the top of the forum bar.

 

[Havasu Dave]

This calculator to play with final ratios: Burris Racing Jackshaft Calculator

This link shows the math: Speed Calculator For Go Karts and Mini Bikes


Pi * tire diameter = circumfrence.

Circumfrence / 12 = circumfrence in feet.

Engine RPMs / Gear Ratio = Wheel RPMS (wRPM)

Tire circumfrence in feet * wRPM = feet per minute.

Feet per minute * 60 = feet per hour.

Feet per hour / 5280 = miles per hour.

 

[minimoto18]

Thank you. That burris racing site helped the most I just typed the size teet on my mini bike and that's 6.00 ratio and then changed the teeth around for the go kart I'm gunna go with a 14 tooth for the cart it will have 5.00 ratio and I think I'll have enough hp to get it goin thank you again!