I'm ordering new 630 sprockets and a chain for my cb750k7. Is a o-ring chain really necessary?
Back on point:
1. The 750 K7-K8 were designed for a 630 O ring chain with no clearance issues at all. No conversion activities when fitting a 530. The spacing of the sprockets are designed in.
2. You can use a non O ring chain as well. It is a bit messy with chain lube flung into the wheels and swing arm.
3. With a O ring you use a "chain wax" type lubricant to stop the side plates from rusting. You do not want a solvent based lube that will attack the O rings.
4. There is no chain oiler on the K7-8.
No matter what size chain you go with, proper alignment will slow down sprocket and chain wear.