Hi there - I owned a mono-shocked 500/4 some years ago. Geometry was based on the RD350LC.
See the link to my intro page on the UK SOHC site for some piccies & an article about the 'bike from a UK magazine. Clearly it has the bracing above the swing-arm that you don't want, but the tubing looks thinner than that used in your picture & it certainly didn't look cluttered as the back-end was jacked-up quite a way.
Anyway, there may be some info that is of help in the article.
Good-luck!
Andy - that post is quite difficult to find so I've copied it onto this post (hope you don't mind)
Steve
Andy said:
I was a student in Manchester in 1992 and the 500 was my first big bike. I knew nothing about CBs at the time but was about to take my bike test and needed a large capacity bike to avoid the rumoured "large bike test". It was a toss up between a SOHC CB750 or the CB500 and the insurance costs meant that the 500 won.
I had no idea that it wasn't standard (!). Started to learn about that when I looked for service parts for the forks and brakes, then got a manual and noticed the differences.
Essentially it is a 1974 CB500/4 in a modified CB500/4 frame. Back end has been mono-shocked. Seat is a Kawasaki Z650. Front end CX500. Tank from a 550. Modified wiring loom, and I think the clocks / idiot lights are from a larger CB - this always annoyed me as I love the idiot lights incorporated in the handlebar clamps and was never able to track down a set!
Front -
Left (no exhaust) -
Right (no exhaust) -
Rear -
I didn't work out much more about it beyond that, just rode it and enjoyed it - although had endless problems keeping the battery charged so I did a lot of pushing and bump starts too. On the plus side it was always one of the coolest bikes parked up at the Uni - and years later on a visit back to see friends I met someone who told me they always used to look out for it and wish they owned it!
In 1994 I sold it on to someone from Bradford and that was that - until 2002 when I was idly flicking through an issue of Classic Bike in the newsagents and a numberplate caught my eye. I had actually turned the page and then my brain caught up and recognised plate and the view and gave me a start - yes, my bike in the mag and a full three page article from the guy who originally built it.
Links to the article below -
Page 1 -
Page 2 -
Page 3 -
- hope they are clear enough to read. I dropped the guy an email to let him know I had owned it and sold it & filled in a a few gaps for him. Now I'm coming full circle and trying to get an old SOHC back on the road again!
Andy