DOHC cb750k exhaust interchangeability?

[zack]

I just got a 1981 cb750k that's in great condition BUT for the exhaust. The pipes and headers are rusted through (and I don't think they're the right ones anyway--they are 4 into 2). So I am shopping around (craigslist, local hobbysists, etc) for an original exhaust system. Here's my question: are the exhaust systems interchangeable among 1979, 1980, 1981, and 1982 DOHC cb750k models? cb750c? cb650c?

What about other cb750s, e.g., would the exhaust system from a 1981 cb750c fit right onto a 1981 cb750k?

Is there any chance that the full exhaust system from a 1981 cb650c would fit right onto a 1981 cb750k? What about from a 1981 cb750c onto a 1981 cb750k?

Right now, I have solid leads on full exhaust systems from a 1981 cb650c and 1981 cb750c. Both of those are affordable and in apparently good condition. I would greatly appreciate any insight. If anyone has such a system they want to sell, I am a prospective buyer.

[LukeM]

The engines should be the same from an exhaust standpoint across the DOHC years (as far as exhaust port spacing, etc).  The difference would be 4 into 4, 4 into 2, and 4 into 1.  Also, there may be some changes in how they are mounted to the bike (different bosses on the frame, different tabs on the exhaust pipes).  There may be spacing differences between the CB650 and CB750 at the engine.  Best guess is to do a side-by-side comparison and see.  Check spacing, diameter of the pipe, how they will attach, the header spacer thingies that sit between the clamp and the pipe, etc.

If you have a good line on both of these prospective new exhaust systems, and they're nearby, why not see if you can get them, take off your current system, and see if the new pipes will fit?  If that's not an option, it does make your task a bit more difficult.

Not much help, perhaps, but that's how I'd pursue it.  Good luck, and keep us in the loop.
Luke M

[zack]

As a follow-up, in case anyone else is ever wondering, it worked. The exhaust from a 1981 cb750c fits onto a 1981 cb750k. No problem.

[Re-run]

Huh I missed this. Yeah as you know, they will interchange. Only thing would be the mount points that you might have to fab a little. Glad you got something to work for you.

[6Blackie6]

Yes Thank you. I have been trying to figure this out also. Looking for a 4 into 1 for a 1980 CB750c. Now I can feel confident when ordering.
Cheers

[Maz]

Just for info, the CB900 systems will fit too.

Maz

[shinyribs]

Dohc 750,900 & 1100 all use the same stuff. Single cam and twin cam pipes will bolt to either engine.

But, if you hang SOHC pipes and a dohc they hang down real low. If you try to hang twin cam pipes on a SOHC they might crash in to the frame.

Muffler/megaphone mounting brackets are obviously anyone's guess. Two totally different frames

[shinyribs]

Carpy's pipes that he originally listed as SOHC "Yoshi" style, which now he claims fits dohc ,too. Which it does, if it's what you want.

[shinyribs]

Same bike with a proper dohc Mac header. Muffler is HUGE, but it's a slip on, and the header tucks tight like it should.

[shinyribs]