First up: I am a rider, not a restorer…

I assumed that all my 1972 bikes were K0s,  1972=K0, 1973=K1 and 1974=K2 (seemed reasonable to an engineer like me).

Not the case. It seems that the K0 was only shipped in the USA, so any UK K0 was either an import or extremely rare.

The differences are important if you are trying to refurbish or restore one of these (not least in the price and availability of the parts).

Many thanks to my good friend Bryan Jones for this summary:

1. Small reflectors on the headlamp ears with 5mm thread (later big ones were 6mm)
2. Round pins on the electrical panel block connectors
3. Forks have the internal threaded bar from the top nut to damper rod
4. Different pattern on seat cover (large squares)
5. Hook on seat lock with different lock on frame
6. Side panels should have a transfer underneath the 500 four badge saying “Honda Motor Co; Tokyo Japan”

Here’s a K0 seat that I bought on eBay.com about 10 years ago:

Compared with the K1 seat fitted to the bike:

Note that the K1 seat has a badly fitted cover and no strap fixings.

 

So, I have a K1.