Got around to installing a Wolo Bad Boy air horn this past weekend. Picked it up at Harbor Freight for $30 with one of their 20% coupons. They even tossed in a small LED flashlight for free.

Separating the compressor from the horn seemed a little tricky at first, even with all of the posts i read here and elsewhere.

The outside plastic casing around the compressor didnt just pop open. The plastic i believe is sonically welded. I made the mistake of taking out the 2 screws that hold the brush cap on the end of the compressor and took it off. It made for a slightly easier time of sticking a screw driver into the small separation in the outside cover. In order to get the cap back on and the brushes pulled back to fit over the commutator, i had to stick 2 small allen keys down through the holes in the top of the cap. Piece of cake after that.
Theres really no need to take the cap off or to be gentle with removing the plastic casing. Its getting thrown away anyways.

Next up was pulling the compressor off. It pulls straight away from the horn and not up as i read elsewhere. (maybe this might be different for the stebel) There is a small plastic bushing that holds them together and a small brass dowel. You can toss both of them if you want.

I then took my dremel with a cut off wheel and cut the rest of the casing away from the horn. Just be careful not the cut into the body of the horn. You just need to take the curved sections of the compressor casing off, so you can fit the horn behind the cowbell.

I just happened to have an 1/8" NPT and 1/8" NPS pipe tap. For the non machinist or plumber, the NPT tap is tapered and the NPS is straight. I used the NPT tap on the horn as its possible to get the tapered tip far enough into the hole to tap the threads. The compressor was a different story. I used the straight pipe tap there as the hole is not very deep. I then took a couple of 90 degree 1/4" push lock fittings and threaded them in. I put some teflon tape on the threads to help seal things up. Despite the straight thread on the compressor, the brass fitting i used tightened up just fine. If it hadnt, i was planning on putting some red locktite or RTV sealent on to keep it from backing out.

I then mounted the compressor under the right side cover on my 08 EGC. Left side was a little crowded with the fuse box and the radio shack alarm mod i did a while back. It may be the better place to mount the compressor if you have the room.
I removed the crash bar torx bolt as shown in the pictures and used a 5/16 x 2.5" fully threaded hex head bolt. I used a nut and washer to space the compressor away from the frame and tightened things up. The mounting instructions that come with the Wolo, do say to mount it vertically.

Cramming the horn into the cowbell was like trying to get 5 lbs of **** into a 4 lb box. I removed one of the slide on nuts on the bracket that the cowbell mounts to and just used the one mounting bolt. I then pried the sides of the cowbell open a little. I thought about taking the drummel to some of the plastic, but really didnt want to butcher it up. It went in far enough that you can only see the very bottom of the horn. I used some heavy tie wraps to keep the horn from coming back out and another tie wrap through the hole where i left out the bracket mounting bolt and nut. You cant see any of this when the cowbell is mounted back on the bike.

Next came the wiring. I picked up an inline fuse holder at the auto parts store for $3.50 and some 20 amp fuses. I wired directly to the positive side of the battery and also ran a lead from the negative side of the battery straight to the compressor. Wiring diagram shows that you can run to a ground on the frame, but it was just as easy to use the battery.

I tie wrapped the relay thats included with the Wolo horn to the battery tray and wrapped some electrical tape around all of the connections. You can see the relay in the pic of the compressor.

I cut off the spade connectors from the original wiring that went to the horn and just used some butt connectors for the new wiring that goes to the relay. If i was a more patient man, i would have soldered them and used some shrink tubing. The new wiring i used was 14 ga. stranded copper and its far enough away from the engine, that i dont think the heat will be an issue. The wiring sleeve thats on the existing horn wiring reached far enough to the frame just near the seat. The butt connectors are tucked in, tie wrapped and out of site. Once again some patience, solder and shrink tubing would make for a more pro looking install.

When i press the horn button, i do notice a very slight delay. Im assuming its from running the 30" of 1/4" tubing from the compressor to the horn. Its not much of a delay, but its not an instant beep as it was with the factory horn. If i just press and hold the horn button and not tap it, you can barely tell there is a delay. Possibly a shorter run of hose or a larger diameter tubing would help. I might change out the 1/4" tubing fittings for 3/8" just to see if it helps.

Id say the new horn is probably 2-3 times louder than the stock horn and was worth the upgrade.

 

Nice job you did, love them horns, wakes up the cagers real quick. Have the same one installed under my right rear saddlebag along with a Howards Big horn (compressor in fairing) and Fiamm lowtone in the stock location. You can never have too loud of a horn when grabbing the attention of a cager thats about to take you out.

 

Great job, NOTL. I spent a large part of my Saturday this weekend doing the same on my 09 UC. Put the compressor in the left side cover, fit nicely. Unfortunately, when I fired it up and pressed the button, it sounded like Granny passing gas in church. Even using the shop compressor, the horn would sound from only one trumpet. While that was kinda loud, it certainly wasn't enough to wake up a sleeping cager. I didn't check the horn prior to separating it from the compressor, so I don't know if it was a bad one out of the box or if I screwed it up. I guess I got a $40 practice run. I don't think that Harbor Freight is gonna be receptive to exchanging it. The horn is welded to the plastic cover of the compressor as you said, so you do have to be a little careful splitting them. Maybe the second attempt will turn out better. Anybody need a spare compressor?

 

PM Sent for the compressor

 

Nice job I've been thinking about mounting one behind my right side saddle bag, in addition to the OE horn, but this a nice alternative. The larger tube may make things worse as there will be more volume to fill. A good test tho, keep us posted.

Thanks again for your write up.