Hi everyone, I have just got some futura se mechanics and was working out my gear ratios. I am going to put an O.S. 91 C Spec in it which has a rpm range from 2000 to 16000, its peak is 3bhp @ 15000 rpm.
As it is now the gearing ratio is 1 to 11.1238 which means at 1800 rotor rpm the engine is doing 20000 rpm not good.
So before I go and buy new gears I was after some info on engine rpm.
Should I try to make the engine do its peak at 1800 rotor speed or do I run the engine at a lower rpm?
Any help would be appreciated.

Sparkhead :stupid:

you should find a ratio getting it to 1 : 7.75 to 1 : 8.4 depending on you muffler/pipe but you want to be at least 1650 to 1700 RPM

Thanks flmgrip

the standard gear ratio on the futura SE is 9.23:1 , i don't think you're checking it properly, i fly my yx80 on the above ratio without changing gears, but i'm going to put the 25 tooth gear on soon. 8.13:1
c-ya Ron

have you got a 42 tooth main cog or 48