[dcb]

well I might have a two stroke available, I looked up the ratios for the gs250 and I am liking them better:

gear, ratio
1, 2.5
2, 1.625
3, 1.21
4, 1.0
5, 0.863
6, .782

primary reduction is 3.125

it might be trickier, but the ratio of 1st to 6th is 3.2, which is nice and wide (and it bolts up and lines up already).

If I tapped into the primary reduction, at 3500rpm, with my 15/37 sprockets, I would be at 42 mph. If I can bodger a 27 tooth rear sprocket then I'm at 57mph.

Or sprocket and chain interface directly into the secondary shaft somehow with a suitable ratio for the existing wheel sprockets (maybe 2:1?). I see some dissassembly and welding of sprockets to transmission shafts in my future

Christ, you still have the gearbox for that honda? Care to get a handle on the ratios?

The secret might be sealing the stuff at the motor shaft behind the sprocket, or if not sealing, adding a slinger ring and any necessary internal baffle to control the oil. If the motor shaft is above the oil level then it should be livable and the chain would stay plenty clean and lubed.