What size gear?

[ineed2fly]

What size gear should I put on my rear axle, 5.5HP engine, top 5000RPM ungoverned, around 3500 average, 16 inch rear tires, 250ish cart and rider. I know the 40 on there is too low, but should I go witha 60? Or more like a 70?

[ineed2fly]

Help!

[kibble]

What size is the driver sprocket?

[ineed2fly]

12 off the clutch

[kibble]

Ok, well, if you want a little more top end, you'd go with the 60. If you want more power, you'd go with the 70.

According to the calculator (http://www.diygokarts.com/speed-calculator.html) with the 60 @ 3500RPM you could get up to 33MPH

With the 70 you could get up to 29 @ 3500.

If the total weight is around 250, I think the 60 would do ok. I have mine set at a really low ratio, <5 actually, I don't remember the exact number as my axle sprocket is an odd number. I weight about 170 Plus the kart, which is quite heavy. I think total it would surpass the 250 mark. It still picks up pretty good. The motor is a bit bigger though at 9HP, but I think you should be ok with what you have.

[ineed2fly]

So I should probably go with the 60 then?

[kibble]

I think it should be ok.