I assume that besides the gears and shafts pictured, he had so swap in the shifter drum from a 6-speed? Anything else? Are the shifter forks etc compatible?
Even just any small bore increase would be nice with the 6-speed, stroking it is great but sounds like it requires more intake & exhaust work. Are there other Yamaha heads that would drop on?
Well, we'd have to grind a groove into the TW shaft for any 6-speed. So what other engines will such a shaft fit into?
dual-purpose:
TW200 28mm carb 67X55.7 2-valve 5-speed 9.5:1
XT250 is fuel-injected. 74X58 5-speed ??2-valve?? 9.5:1
WR250R is fuel-injected. 77X53.6 4-valve 11.8:1
WR250X is fuel-injected. 77x53.6 DOHC 4-valve 11.8:1 6-speed
motocross:
YZ250 is 2-stroke.
YZ250F is 39mm carb, 77X53.6 5Ti valve 5-speed
off-road:
WR250F is carb. 77X53.6 5Ti valve 12.5:1
TT-R230 is carb. 70X58