Puzzle for you gurus out there...

[Kookopelli]

I bought a 1980 CB750F from the brother of a guy who died about 10 years ago who was a bike mechanic. It has been in a storage locker since he died. The history of the bike as close as I can piece together is that he replaced the engine with a 900F engine with 1000cc top end and then went to an 1100cc top end or just an 1100cc cylinder heads on a 1000cc cylinder/pistons. Not sure exactly what I have.

The engine serial no is SC01E-2206125,  which is an '81 CB900F as far as I have been able to figure out. I don't know how to tell what the cyllinders, pistons or heads are without finding a part number, but I don't know where to look. The carburetors have a number on the side that is 56A[A]UFT and measure 30mm inside diameter on the cylinder head side.

Can anyone give me a hint where to look for numbers on the cylinders and the cylinder heads? What about the rocker arm covers? Are they specific to the heads or will one from another size engine fit? They all look the same to me. I would be able to figure that out if I could figure out what heads this thing has.

Right now everything is in pretty good shape except the carb boots to the head. They are cracked and I want to replace them, but haven't been able to figure out what engine parts fiche to look at...could be 1000cc or 1100cc. The boots I took off measure like 36.5mm inside on the carb side and 32.5mm on the cylinder head side.

I know I could figure most of this out if I tore the engine down, but I don't want to do that unless it needs it. I have connected a battery to it and it spins over nicely and the compression is great on all cylinders. I plan to change the oil and replace some missing electrical parts necessary to make it run and fire it up. If it runs ok, then I will proceed with the rest of the restoration. If it doesn't, then I will figure it out from there.

Some of the things I know it needs is rebuilding the brakes all around, new sprockets and chain, I plan to rewire it with minimal wiring and cafe or bobber the bike and have ordered new coils, rectifier/regulator, starter solenoid and ignitiers set. Don't exactly understand the initers, but it seems like I need them.

If anyone has any insite as to what the 'thing to do' with these things as far as putting larger pistons/cylinders/heads on the 900 engine I would appreciate it. If maybe I should look for another forum, please point me in that direction.

Thanks a bunch.

Kook

[TOOLS1]

The only thing I know of that would have some identifying mark on it would be the cylinder. It will have the cc's on it somewhere. I think all the DOHC engines used the same head. You could go to Westernhills Honda's web site and look through the parts fiches and compare part numbers to see what crosses over to what. The only real way to tell what is in that engine though is to take it apart.
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