New Build...Sprocket, Clutch Ratio Upgrade

[Joe37]

Im restoring a Carter Bros. 2506-3016 Go kart and I've had some what of good luck finding parts for it.

My question is... What sprocket and clutch should I buy?

It originally came with a 72 tooth sprocket and a #41 10T clutch, which seems to go about 19 mhp on a 3600 RPM engine. I'm going to buy a 6.5 hp engine.

It has 6" split rims and 15x6x6 tires in the rear.

I'd like to increase the mph to atleast 25 without sacrificing acceleration. I wanna stay somewhere in the middle.

A #35 60 tooth sprocket and a 12T clutch seems to be the way to go, but I cant find a #35 60 tooth sprocket with a 2" center hole, 5/16" bolts on a 2 13/16" bolt circle.

It seems I'll be going with a #41/40 Sprocket with 54 teeth, and a #41 3/4" clutch with 10 teeth.
Is that ratio okay, with my 15x6x6 rear tires?

Thanks for the help in advance.

 

[OzFab]

A good, balanced ratio is around 6:1; going higher means you will lose acceleration. There are a few ways to increase top speed without sacrificing acceleration:
1. Go for the higher gearing but, as I said, you will lose out on acceleration & also risk damage to the clutch
2. Fit a torque converter: You can stick with your current gearing & have the advantage of the overdrive feature
3. Remove the governor from your existing engine which should increase the max RPM from 3600 to 5000 &, therefore, increase the theoretical top speed from 22mph to 31mph