Topic: 1977 CB550K different from 1978 CB550K? K1, K2, K3?

[gretjenhelene]

I have seen the CB550K models referred to as K1, K2, K3 and wondered whether these are significantly different.

I have a frankenstein of a bike and just figured out that the body doesn't match the engine- body is a '77 vin: cb550k-2007351
& engine is a '78 #:cb550E-2114966
Also, by the looks of it, I think the tank is from an F2.

I suppose they could have interchageable parts but maybe not.
Warn me if I shouldn't assume their compatibility.
thanks

[TwoTired]

Both the 77 and 78 Cb550K models are both K3.
They used the same shape tank as the F models, the petcock and color was different among them.

Minor differences between them, mostly in the trim/color area.

The 78 was available in red, side cover decal said "K" and had a gold stripe.  And it had a dual contoured seat, instead of the flat 77 model.

Engines are identical, apart from serial numbers.  Carbs were set up slightly differently.

Cheers,