440 550 Couplers on a SJ?

[wildman326]

What's the story here? Do they need to be a certain size? Do any 550 couplers fit on a SJ?

Help!?

 

[sflsurfrider]

umi makes kawi style couplers for yami motors. you cant just take a set of 440/550 couplers and thread them onto the crankshaft and shortshaft, but then, ive never tried

 

[SuperJETT]

Yamaha's have much bigger threads.

I have the UMI billet Kawi-style couplers. They are smaller, no performance gain (theoretically yes, real-world no) but they seem to make it easier to align.