Gearing question

[landuse]

I have another gearing question for you all. My minibike that I have made goes OK, but I would like a bit more torque to save the clutch a bit and to make it more fun for my daughter. The setup I have at the moment is 16 teeth on the clutch, 38 J/S in, 14 J/S out and 48 on the rear wheel. This gives me:

38/16 * 48/14 = 8.142 ratio

I was looking to get a smaller J/S out sprocket by going from a 14 to a 12 tooth, but it would be a bit too small. The boss is 25mm in diameter, and I would have to have a 17mm inner hole. This would leave me with a 4mm wall thickness and I still need a keyway.

I then thought that I would change the 38 tooth to a 45 tooth sprocket, but the standard inner hole diameter is 20mm, which is bigger than what I want. A 40 tooth sprocket has a 14mm inner hole diameter, which is fine for me because I can increase it to 17mm. The gearing with the 40 tooth sprocket would be:

40/16 * 48/14 = 8.57 ratio

So....I would like to know if it would be worth my time and expense on the 40 tooth sprocket just to go from 8.142 to 8.57 in my gear ratio?

Thanks in advance

Edit: My wheel rims are 12" rims, so my tires are quite large for a minibike. My avatar is a pic of the bike

 

[qtband]

Have you checked out the sprockets on mcmaster.com? You can get just about any tooth configuration with just about any bore size. Just a thought.

 

[B.M.800]

Personally, I would try an get 10-1 ratio, thats how my minibike is geared. It went somewhere around 25mph, but after fiddling with the govoner I think its around 28-30...

 

[landuse]

Thanks qtband, but i live in south africa so shipping would be too much. I dont have too many options here. Would a 0.4 change in gearing make any differance?