I'm having a heck of a time finding a non o-ring chain for my 75 CB750 K5. I know everyone says o-rings on 550s rub but they do on my 750 also. 5 years ago it was easy to fine a chain. Now its seems like a lot of the major brands RK EK DID tsubaki have switched to o-ring x-ring and say "we do not have much to offer" The standard non o-ring chains you fine say 400cc max..