Smaller sprockets.

alvin l nunley

Premium User
I keep thinking about the post where the guy was apparently running smaller chain sprockets. What would be wrong with a 12/48 = 4 – 1 combination. On 2 cycles they use both 9 and 10 tooth engine sprockets and turn 16,000 RPM. Surely the load would be much less at 6000 RPM? I don't know how much, maybe a 3rd? Maybe less? All we would really need is a sprocket carrier to fit the smaller sprocket. Maybe try it with 219 chain?
Some advantages; less reciprocating weight, slower chain speed, more ground clearance. I see it coming

95 shaw

Premium User
4 cycles turn less rpm, so they need to produce more torque to have comparable horsepower.
Couple that with power stroke every other revolution instead of every revolution. Means large torque spike when engine fires.

I run 9 tooth sprockets on my open 4 cycle with 35 chain up to 9,000 rpm. Engine has way less torque down low, compared to a clone. It lives, for a short while, anyway.
219 chain might be pushing your luck.

Not sure where chain has anything to do with reciprocating weight.


Dawg 89
That with a little imagination . Demonstrates the piston movment with a long rod . In my vison anyway .