I take it this bike will have a cetrifugal clutch Terry, you might have to run beside it for a while before hoping on
G'Day men, what I've got is two EBay Chinese two stroke bicycle engines, both 65cc, running short chains from their 10 tooth countershaft sprockets to a layshaft, where the final drive sprocket (14 tooth) runs to the rear sprocket. (44 tooth)
One engine has a centrifugal clutch and a recoil (pull) starter, the other engine has a manual clutch only. The deal is, I start the engine with the centrifugal clutch, use that engine to get off the line, (will go ok on the flat or on a downhill surface, but you gotta pedal if going uphill) then once it's sufficiently mobile, dump the clutch, and fire up engine #2.
I took it for a ride today, with the previous 10 tooth layshaft final drive sprocket it was only good for around 35 MPH, but with the 14 toother, it's much better. I'm yet to hook up a speedo, but my "seat-of-my-pants-meter" tells me that today I was easily doing 45, and being the best part of 280 pounds, I'm hoping my 150 pound cuz, Rodney, will be able to improve on that somewhat.
Also, I'd like to further increase the final drive ratio by upping it at least another couple of teeth or more, maybe even a 20 toother on the salt? With no gears, but 6 miles of flat smooth salt, it'll have plenty of room to wind right out, so maybe 60 MPH(+) might not be out of the question? Pics and a short vid soon! Cheers, Terry.