Dropping a CBR600 in a cb750 frame

[Iceman16]

Hey everyone,

Just about to finish my 1980 cb750. So, starting to think about my next project. I own another 1981 Honda cb750. I stripped it down to the frame. So, here is my thought. I want to throw in a CBR600RR engine in the frame. I have the metal fabrication skill and feel fairly confident I can get the geometry correct. My main concern is getting an engine with too much computer for me to deal with. I don’t want to get a very modern engine that requires a ton of work with the ecu and what not. So, what year do you guys think I should get? I know this is a DOHC forum but I’m sure a lot of you have knowledge on something like this?

 

[Loose Chain]

If you want to do that kind of an engine swap then you are going to have to deal with the electronics. I don't know where you are getting the engine but I would suggest getting the entire bike and transplanting the complete wiring harness with switches, ignition switch, lights, basically everything electrical into your bike. If you aren't comfortable around electrical you will be pulling your hair out if you do it any other way. If you don't have a donor bike then don't just buy an engine and think it will be an easy thing to do. You got throttle bodies, fuel injectors, electric fuel pump, throttle cables, clutch operation and on and on. Big job. Mounting the engine in a frame is the easy part.

 

[dirtdigger]

Well 2000 was the last year of the carbureted cbr600 after that it was efi as the cbr600f4i. Any of the cbr engines are going to have electronic ignition and will require the wiring and the ignition module. The engine cylinders lean forward way more than the old 750 did so its going to look funny in the front cradle of the 750 unless you do a bunch of reengineering of the frame to take the stress and use the engine as the stressed member as the cbr's were. I understand your want to do something different but these old generation frames really are heavy and not that stiff and it would take some real engineering in the backbone and steering stem area to make it as a stressed member with the engine unless you completely rebuild the down tubes and cradle to match the cylinder cant, which would look kind of funny in my opinion.

 

[Loose Chain]

The CBR600rr Started in 2003 I think, which is the engine he wants to use so it will be the "dual stage" fuel injection.

 

[dirtdigger]

He also asked what year he should get without a lot of wring so I gave an option...

 

[Loose Chain]

He said he wanted to use an RR engine so that is what I was going on.

 

[dirtdigger]

Well I guess he has options now