Kz550 Kz650 header compatibility revisited

This has come up a bunch of times, and the answer was always no they are not swappable. But why not? I think it's only because the spacing between cylinders is different.

The pipes use the same crush washer gasket, and the mounting flanges are shared as well. As a matter of fact, from a serarch on buykawaski.com, it appears the 550, 650, and 750 all share the same flanges and gasket washers with many models.

My buddy recently bought what was advertised as a 4-into-1 header for a 550. I was mocking it up to a spare bike I have (which has no exhaust at the moment), and the pipes were all too far apart. So I asked my friend if the guy also had 650 parts, and he said yes. I suspect this header is for a 650 based on the pipe spacing. But the pipes and flanges all seem to be the same size as ones for a 550. (I compared it against some spare 550 header I had.)

With a little coaxing I was able to match the pipe spacing on the headers to a 550 spacing. Later, I will try to mount it to the spare 550 motor and see if it's doable. The rest of the header seemed to line up with the frame pretty well. The headers are using longer primary tubes, so the 4-to-1 connection ends up a little further back than on the other 550 headers I have, but I don't see a problem with it.

Anyone else done this?

I would say you are correct but usually the person asks, "Will a 650 header bolt onto a 550?" the correct answer it still no it will not. Now if the person asks, "Can I get a 650 header to work on a 550?" then that answer would be yes, as you can get anything to work with enough ingenuity and tools.

What about the vertical length of the header pipes? Will the system hang down below the bike on the 550?

baldy110 wrote: I would say you are correct but usually the person asks, "Will a 650 header bolt onto a 550?" the correct answer it still no it will not. Now if the person asks, "Can I get a 650 header to work on a 550?" then that answer would be yes, as you can get anything to work with enough ingenuity and tools.

Aren't those two questions the same?

I assume you mean a 650 header will fit a 550, but not the other way around.

Are you saying the distance from the head to the bottom of the motor is longer on a 650, so that is why a 550 header won't fit on a 650?

So maybe after botling it up, the headers will hang to low beneath the bike and reduce ground clearance?

martin_csr wrote: What about the vertical length of the header pipes? Will the system hang down below the bike on the 550?

When I was mocking it up, I didn't notice any great amopunt of hang down, but I wasn't exactly looking for that either. I'll check it out when I get a chance later.

It's possible the header we have is a 550, but the seller was trying to fit it onto a 650 before he gave up. My buddy said there is a 650 in the ad without an exhaust system. So I guess it could be either way 550 or 650, and we'll just have to try it.

Well I was able to tweak, what I think are 650 pipes, pretty easily to fit the 550 head. But as you guys said the results are not the same as using a 550 header.

The 650 pipes hang down roughly 1/2 inch lower, and stick forward maybe 3/4 inch at the lower elbows.


Here's bottom clearance for a 650 header on a 550.


Here's bottom clearance for a 550 header on a 550.





Here's front clearance for a 650 header on a 550.


Here's front clearance for a 550 header on a 550.


Here's front clearance for a 550 header on a 550.


Here's front clearance for a 550 header on a 550.

Way to go Lou. Just to add the ZX600 C Model (1985-1987) should also have the same spacing. I have 2 of these headers, and have got both to fit, but didn't check how far they hang down.

Here is how close the street system on Elvira sits to the engine:






Good luck on your fitting issues.

Thanks Corey,
That pipe is nice and tight against the motor!