K75S Horn Mounting, Options

[evillerich]

Hello,

I'm continuing on my 1987 K75S endless rebuild project. After appearing to resolve the shaky fairing issue (it's nice and tight now), I'm turning my attention to the horn. I'm 93.2% sure this bike had a tip-over at some point due to the fairing condition and am not convinced the horn was ever mounted properly. The PO had it mounted under the headlight, using the bolt that ties the two fairing sides to the headlight frame. Seemed to have a lot of movement and I don't really like the weight of the horn bouncing around on that point. The problem solved itself with the metal bracket that tied the horn to the fairing bolt location failing due to metal fatigue, leaving the horn dangling.

In my research, I see mention of the plastic headlight frame being used to hold the horn, however, I can see no sign of any connecting parts that would have tied-in there. And parts seem scarce, if even available. I'm at a bit of a loss as to exactly how the horn is supposed to be mounted. I'm ready to find my own solution.

On the triple tree, I do see two unused bolt holes (one on each side). I'm considering some sort of bracket that would use these bolt holes and provide a central mounting point for the horn.

Wondering if there are any known clever solutions out there. I'm willing to try an aftermarket horn kit if it comes with a mounting solution.

Thank you!
Eville Rich
1987 K75S

[Pauls1150]

No, I don't believe the factory ever mounted it near the headlight...
It's been many years since I had one, but I seem to recall it being mounted to the fairing or frame, just ahead of the engine or by the cooler? Couldn't find any decent pictures of that, but here's the MAX parts fiche picture that may provide a clue...
Paging Dr. Lee and Dr. Paul G....
K75S horn parts.png

[98lee]

Eville,


The horns DO mount to the headlight frame. There are two slots in the frame, one near the lower right of the headlight and one a little more than half way up on the left.

The flat bar (7/8” x 3 1/2”) that you see attached to the horns in Paul’s post slides into these slots. It is secured by a square nut, that slides into a pocket next to the slot, and a bolt. You can mount one or two horns since there are two slots.

None of these mounting parts needs to be exact, so you can fabricate the parts or source them from a hardware store.

The factory uses an 8mm x 20mm allen head bolt with lock washer plus an 8mm square nut (13mm x 13mm). But you can use a 5/16 x 3/4” Hex or allen and a 5/16” square nut. You may need to grind a hair off the side of the nut to get it to fit properly in the pocket. It does not need to be exact.

The factory uses .088” thick flat bar, 3/16” will work fine, must be under .225”.

[Pauls1150]

Thanks for jogging (or flogging) my memory!

[evillerich]

Eville,


The horns DO mount to the headlight frame. There are two slots in the frame, one near the lower right of the headlight and one a little more than half way up on the left.

The flat bar (7/8” x 3 1/2”) that you see attached to the horns in Paul’s post slides into these slots. It is secured by a square nut, that slides into a pocket next to the slot, and a bolt. You can mount one or two horns since there are two slots.

None of these mounting parts needs to be exact, so you can fabricate the parts or source them from a hardware store.

The factory uses an 8mm x 20mm allen head bolt with lock washer plus an 8mm square nut (13mm x 13mm). But you can use a 5/16 x 3/4” Hex or allen and a 5/16” square nut. You may need to grind a hair off the side of the nut to get it to fit properly in the pocket. It does not need to be exact.

The factory uses .088” thick flat bar, 3/16” will work fine, must be under .225”.

Thanks for the pointers with this. I may try to get it mounted back on the headlight frame. That would be a bit better than where it was. I've stared at the parts diagram over the last few months and tried to puzzle out what each piece is meant to do. But it seems easy enough to get hardware store bits and do some clumsy fabrication/tweaking. I've been looking at the K75, K75RT and K75C horn, too, wondering if there's an option to consider for that as an alternative. I really can't tell how those connect to puzzle through an alternative, which may not even be possible.

[evillerich]

Following up to close this out and hopefully help others:

I used 5/16 hardware - square nut, plus spring washer and bolt. The square nut fit perfectly. Also 3/4 wide x 3/16 metal from Home Depot. Cut a section about 3.25 inches, drilled 5/16 holes at each end (a lot of eyeballing on that, plus shaving/trimming the metal. Cleaned, primered, and painted black. Gave it a ~25 degree bend to help give a bit more space between the horn and downtube, but probably not necessary. Everything came together nicely.

Thank you for the help with this rather obscure issue. Solving this problem completes the success at solving a rattling and jumpy front fairing (lots of other hardware bits for that). Nice and quiet on my morning ride this morning. Now time to move to other matters on the bike.

Eville Rich
87 K75S