The outside width of o-ring chains can vary a lot, some are extremely wide while others aren't. I've been using a parts unlimited brand "X"ring chain with no problems.
The CB650's used o-ring chains from the factory and I believe the countershaft and cases are the same in that area? Also there are different sprockets, some have a shoulder and some don't. I think aftermarket ones typically don't and this moves the sprocket outboard for more clearance
It can be done and its well worth the effort..
