Topic: Engine Help Advice

[DuckFan]

Hey all,

So I'm in the process of restoring a 1976 CB750F. This bike is a PROJECT bike, I'm not sure anything ever actually worked. Anyways, to the engine.

To start, it appears the previous owner poured some kind of sugar or crystalizing substance straight into the combustion chamber as the gas tank has no evidence of it. The pistons were frozen solid and I almost broke the cylinder barrels just to free them due to rusting and that sugary substance. The bottom half looks clean and in order. I thought I was through the worst of it until I inspected the engine case. There is a massive hole in front of the primary drive sprocket that is in both halves of the case which the previous owner JB welded together to "fix" it.
My question is this: Is this engine even worth saving? Am I better off getting a running used engine on ebay? I do want to restore this bike the right way, but my budget is hilariously small. I'm a college student hoping to go to medical school next year. Anyways, any advice is helpful and thank you for reading my post!

DuckFan

[Jerry Rxman Griffin aka MuthaF'er]

Find a spare. Use it's cases and your guts. There are advantages of the guts of your engine. 

[DuckFan]

Thank you for the reply. What years will match? I know 77-78 have some differences but I'm not sure where and what.

[Jerry Rxman Griffin aka MuthaF'er]

77-78 use a double row bearing on the output shaft. The result is an additional 10mm offset so that would require other changes behind it. While a double row bearing sounds nice it would complicate things. Most of the earlier cases will work as long as you have a matching set. There are possible oil return differences so that requires a match too. Pretty much anything can be overcome if you have time, money, patience and a little ability. Beers help too. 

[CycleRanger]

Hey all,

So I'm in the process of restoring a 1976 CB750F. This bike is a PROJECT bike, I'm not sure anything ever actually worked. Anyways, to the engine.

To start, it appears the previous owner poured some kind of sugar or crystalizing substance straight into the combustion chamber as the gas tank has no evidence of it. The pistons were frozen solid and I almost broke the cylinder barrels just to free them due to rusting and that sugary substance.

DuckFan

Sounds like sodium silicate.

[bear]

I'm with calj, get the cases welded.