Topic: 1975/77/94 CB(r)750 K5F

[Spleen138]

Hey everyone! Hoping you all can give me a hand with some stuff.

I've got a CB750 K5 engine in a CB750F frame with a 94 CBR's front end and swingarm.

I'm struggling with getting the front and rear sprockets lined up; suffering a lot of click and clunk going on as the chain pops itself into place on the front sprocket.

If the front sprocket is not locked down, it walks itself all the way off the shaft. I'm assuming its trying to make it to its happy home in line with the rear, and falling off the shaft before it gets there.

It seems like I need an offset front sprocket (left, away from the engine) and possibly, maybe an offset rear sprocket.

Trouble is, I can't seem to find offset rear sprockets for the cbr wheels, and offset front sprockets are a whopping $95 a piece! (No way, right?)

Can anyone shed any light on this situation?

[calj737]

Are both sprockets on the bike currently the same pitch? Are you running a mixed bag perhaps?

You should use a metal straight edge laid against the outside of the sprockets to confirm they're inline or how far out they are. Likely the rear sprocket is much farther left requiring an offset front. CognitoMoto sells offset sprockets, as do many other places. But you need to start with a confirmation that both sprockets are the same pitch.

[Spleen138]

My research tells me that they both came stock with 530 chains, the 75 750K and the CBR. (Edit) Though, I suppose I don't know if someone changed it along the way.

Haven't tried the straight edge trick, but other measurements tell me I need at least 20 mm of offset.

I have only been able to find ~10mm offset front sprockets from various websites.
Someone said there were 20mm offset fronts at cyclex, but it doesn't look like they're listed anymore.

I'm thinking that I'll need to machine down the cbr cush drive, since there is no demand for offset rear sprockets for that wheel.

[calj737]

Careful milling the rear sprocket... If you take it too far inboard, the chain will eat the tire.