Topic: K4 Engine in a K2 Frame

[Freebirdbeachbum]

I recently acquired a CB750 Four for restoration and discovered the frame is a K2 but the engine is a K4. It starts, runs, and stops but it’s tired and needs a thorough refresh. My plan is to end up at near showroom condition.

What special considerations should be made, if any, in the mating of the K2 and K4.

Thanks,

Ken

[bryanj]

If it was a UK model we only had K2 until K6 came along but of course Honda were fitting whatever year engine it was built in

[Alan F.]

That should be a relatively seamless swap, differences should all be minor and internal.

[PeWe]

I have 2 CB750 K2 year 1975. We also got K0, K1, K2, K6...

Both should have engines of 1975

Mostly cylinder and head design that differ. I think the gear selector drum was improved after 1972. Otherwise same parts what I am aware of.

Double row ball bearing was installed on final shaft 1972?
Anyway, a K4 engine a direct swap into a K2.

[754]

 2 main differences , head and the numbers.
 Head will be very obvious even at 20 feet to those in the know. .

[BenelliSEI]

2 main differences , head and the numbers.
 Head will be very obvious even at 20 feet to those in the know. .

754 over rates most of us! I have a ‘76 with a ‘74 motor. It took me months to notice.l.....

[The Lone Builder]

I have exactly the same combination; mine is a UK model.

Everything fits fine; just make sure to sue the correct parts fiche for the engine and there are some small differences.