Changing exhaust from 4 into 2 to 4 into 1

[78cb750-2]

I have a 78CB 750 and removed the 4 into 2 exhaust and purchased a Kerker 4 into 1. The new Kerker pipes seem like they are about 1/8 inch larger then the engine allows in the 4 exhaust holes.

Has anyone undergone this same change on your bike?
Is there a difference in engines from year to year?

Tell me I didn't spend $500 on something that doesn't fit on my bike!

I'd appreciate any advice!

[woodsrider250-2]

Not positive, but I think Kerker only makes the stuff for DOHC 750's (79-82)....That might be what you got.  Almost positive the exh manifolds are the same throughout the generations (69-78 SOHC, 79-82 DOCH), and yes, not compatabile.

[78cb750-2]

here is the link of the place I purchased the pipes from. It states 1970-78 CB750K, 1975-78 CB750F

http://www.dynoman.net/exhaust/kerker-apps.html

Should I have the exhaust ports machined down a bit or the pipes

[woodsrider250-2]

Those guys are a pretty good source for old air cooled stuff!  I'd call them, and see what they have to say.  Maybe you got the DOHC part by mistake?

[78cb750-2]

They don't have a number because they are in the "Lab" all day. Though they are great at returning e-mails. They told me,

"Alin, sometimes the lip of the pipe just needs a little dressing down with a file or there is corrosion in the port. Just filling of the excess on the lip usually will fix the problem.

Let us know if you have any more problems.

Kind regards,"

So I'll try that first. Unfortunately I received the Kerker back in September and didn't get around to trying to mount it until now.

Damn procrastination!