Another UK CB500 K0

[Oddjob]

There is no superceded part number for the horn on the K0 Julie, it's always been 38100-300-023, ( I have a very old parts book for the 500, early seventies and it's that part number in there, be interesting if Bryans K0 parts book says something different I suppose) there are though other horns that look the same fitted to other countries, 38100-300-621 for France and 38100-341-630 Euro direct. The later now supercedes to 38100-300-023 but interestingly the French horn  looks to be the same as yours Julie, not the horn itself, which for some unknown reason looks to be grey where the normal one is black but the cover itself. https://www.cmsnl.com/honda-cb500k0-four-france_model14655/horn-assy_38100300621/ I've also found that if the part number is exactly the same so is the part, doesn't matter if it has the modern part number sticker or the older paper part number inside the bag, made to the same specs as the original.

Look at the hole, it's at the bottom BUT it has 2 crimped sections either side of the hole, the 023 part number does not. It also doesn't appear to be chromed like the 023 part, I'm wondering if the cover has been replaced due to corrosion issues before you bought it. I can 100% testify that my horn I'm currently restoring is original, I've had that cover rechromed before as they tend to get fairly rusty and spotty for some reason, maybe it's the location. Also notice the french version doesn't have the separate earthing wire like 023, I wonder why Honda did that?

Doesn't really matter either way, just thought I'd mention it, the hole makes 100% sense to go at the bottom or it would collect water otherwise and corrode it from the inside out but it still looks the part so no harm done in the end.

[Nurse Julie]

Many parts don't make sense with the UK K0 parts Ken. We have had 2 NOS OEM brake rods, both the same part number, both in identical bags but one was black and the other was silver (BZP). The same applies with the rear sprocket cover for the K0, both same packet and part numbers, one black, one BZP. I know for sure this horn is original to the bike. What isn't original, is the master cylinder cap fitted on the bike, it's now been changed for the correct, original concave cap 😊😊😊😊

[Seabeowner]

Just looked at my 7/71 all original K0 horn. Wiring cut out between 2 & 3 o/c, hole at 6 o/c, one crimp at 10 o/c (and two other crimps at about 3 o/c and 4 o/c) Noticed a couple of other things, but it's still a beaut!

[honda-san]

Early sandcast CB750 horns were fitted on the left side of the bike, were under part number 38100 - 300 - 013 and had the cable exit at the left side and that drain hole at the bottom (as your cover would be were you to re-fit it with the drain hole at the bottom, Julie). I also THINK the same chrome horn cover was used on some of the CB250 / 350 twins of the time. Is it possible that the  chrome cover is not actually the one that was fitted in the factory, rather something that a previous owner has changed and which actually came from a different bike?

As to the black zinc finish that comes on some parts that were originally just a bright silver zinc finish, I suspect they are just later spares production pieces - Honda were using black / drab olive zinc as standard on some parts on the 750F2 of 77/78, and much more extensively in the years that followed on some models and really were not all that bothered about as to whether the surface finish on "spares" parts was exactly as per original; the part would do the same job irrespective of finish.

Nice bike by the way.

Chris R.

[Nurse Julie]

Thanks Chris. The house will look empty of bikes when you next pop in for a cuppa. I can see the floors in all the rooms for the 1st time in years 😂😂😂😂. Not sure I can get used to not tripping over bikes 🤔🤔🤔

[Bryanj]

You cant have that Julie, Graham needs the tactile feel to get around

[Oddjob]

Just looked at my 7/71 all original K0 horn. Wiring cut out between 2 & 3 o/c, hole at 6 o/c, one crimp at 10 o/c. Noticed a couple of other things, but it's still a beaut!

Sounds exactly like mine. One crimp at 10, one at 4 and one at 5 and the hole at 6 approx. My cover has a slight split on the crimp at 4 o'clock so I bought a new horn today just in case. Managed to find one cheaper than the normal price.

Ds one for sale with a dent in the cover and believe it or not but it's more expensive than an undented one, weird.