interesting. I can see why Bacon's 27 tooth on a scrambler would give higher revs for lower speeds, but that doesn't explain why your 16 tooth would only make 50mph? seems you would be running super fast with that, at the cost of a harder start in first and less torque? all in all it depends on what you have on the gearbox too, you can count that without disassembling anything, but it's a little hard to see. just mark one tooth and count as you turn the wheel thru to that tooth again!
so a response that I got in another forum when asking after this sort of thing was
Snowbeard, according to the later parts manual ('59-62), the Spitfire scrambler came with a 21T engine sprocket (as did all solo A10's) but a 16T countershaft sprocket whereas other A10 models came with a 19T countershaft sprocket. If this is the case on your machine, it would explain the high revs, but you would have to take the entire primary off to fix the problem. The upside of this is that 19T countershaft sprockets should be readily available. /quote
then when I finally got to count my teeth I got 21 tooth engine gear, 43 tooth clutch sprocket, 19 tooth drive gear and 46 tooth on my rear sprocket,
to which was replied:
Snowbeard, it looks like you have the standard A10 solo gearing which is a good compromise between acceleration and top end. With that gearing you should be turning about 4200 @ 65 mph and 6400 @ 100 mph. /quote
I also have not seen a 16 tooth cush drive gear offered, not to say it won't happen. is your crankshaft drive gear a cush drive? two lobed? or four? just checking on what might have been done to 'er.
