Frames

[KaiC]

I bought 2 bikes for $400. One is a 1981 CB750C, complete and almost ready to go, the other is a 1982 CB750C and is in pieces. The bike was in a collision and the frame was bent. I have most of the parts I need to put together a second bike but I am missing the frame and front forks. I am a mechanic, but this is my first motorcycle, and I have never had a dirt bike, quad or anything like that so please bare with me as my knowledge is somewhat limited.

Do I have to find a frame for that specific year and style of bike, or can I use the frame from a different model. I have the 750 inline 4 engine and need something that the engine and trani will bolt on to without to much trouble. Any suggestions?

 

[amc49]

First question would be why you're not taking parts off one to make at least ONE complete running bike? Or, what is the infatuation with TWO of them?

In answer to question, you will find more than one frame to fit the engine/trans, but only one type to fit the exact model, the fuel tank bungs, side cover holes and other things are matched to that one bike. The frames start out as basic common ones pretty much but then additional welded on pieces and fittings customize the frame to then work on one model only. Such as a C frame only working on C bikes, or F frame ditto or K frame ditto, etc. The frames change up to fit the different tanks, side covers, seats and other detail pieces for that specific model.

 

[KaiC]

When I bought them, I bought them both from the same guy. The one bike already runs and is complete. It just needs some tuning and cleaning and a couple parts the just need to be new (tires, air filter, etc.). The parts on the first bike are actually in better condition the the other. I was just looking at putting another bike together for my dad. I just wanted to find out some information, I dont mind having to build up something with other parts. I can sell the stuff that dont fit and get what dose

 

[amc49]

That's often easier said than done when i comes to re-equipping a different frame with what goes on it. Complete bikes sell better and finding OEM tanks and side covers and tailpiece parts to go with a certain frame can be quite expensive in certain cases. Certain plastic body parts can kill you now and finding good tanks in an era of corrosion making ethanol laced fuel is now an issue much bigger than it used to be. Some of the front fork stuff does directly interchange but lots of changes means that indiscriminate buying of forks can get you easily into trouble with mismatched parts too. Wheels can determine the forks that have to be used. The bikes use 35, 37, and 39 mm. forks and the triple clamps vary just as much if not more since two spreads between them are used. Several ways to go there but it can be a quagmire.

The 'C' bikes were pretty plentiful, I'd definitely look to buy another frame to match parts you already have, it will go much quicker and easier. The frame determines the title too, something else to think about.

 

[KaiC]

Ok, thanks allot. Thats great information. As I said before, I am a mechanic so I no how to work on things and have a good understanding of how things are supose to work. But as for the specifics, I wouldn't no where to begin. As for some of the covers and things like that, I also do fabricating, I can always make whatever I need. Im currently making a new seat pan for the completed bike.

Again, thanks allot for all the information. This is all extremely helpful. I think I will definitely look for the proper frame to make things allot easier.