When I bought my first new bike back in 1977 at the age of 18, I had my fathers words in my mind, “Make sure that every bike that you own has good lights and a good horn”. That BMW R75/7 had both.
Here we are 40 years later and I have just bought the new Ducati Supersport 939. This bike comes with some decent lighting as standard and has the LED strip for daytime conspicuity, nothing needed there then. The horn on the other hand was like Mickey Mouse farting! It could not be heard over the sound of the engine on tickover. Bikers who have visited this area will know that there is one huge danger on the roads in this part of France – Belgian car drivers. A good horn stops them in their tracks.
The horn of choice was the DENALI Soundbomb Split. I went for the split as there is not much room on the Supersport and with the split I could use both sides of the bike. Here is the kit:
The part on the left is the dual tone air trumpet, the fitted aluminium bracket is my construction – more of that later, centre is the compressor and on the right is the air hose to connect the two. The kit also came with a relay which I threw away and fitted a better quality one.
The trumpet was fitted under the left fairing fillet panel with the home made bracket.
These are the two bolts that hold the fillet panel on, remove them and pull the panel rearwards and it comes off.
The following two pictures show the bracket that I made from aluminium to hold the trumpet. This is bolted with a rubber packer so that it is insulated for vibration from the bracket.
The bracket holds the trumpet out of sight below the fillet panel, and attaches to the top radiator mount and the bolt that holds the existing horn in place. Here it is in position.
The trumpet must have some clearance around it so that it when it is in operation it is not able to touch anything. The original horn is left in place and left connected, it can be seen in front (right in picture) of the bracket leg.
The compressor was fitted on the other side of the bike, also on a bracket bolted to the top radiator mount. The radiator expansion tank hose is a hindrance to using an allen key on this bolt, so a hex head bolt was fitted.
The relay was operated by piggyback wires from the original horn. The reason for keeping that horn is that the electrical system will not operate the Soundbomb alone as it draws too much power and the bike thinks that there is something wrong. The compressor is wired to the battery through the relay and a 25 amp fuse. Note the carbon fibre mounting bracket on this side. I have to thank my aircraft career for the ability to make brackets!
The horn button on the bike is now a thing to be wary of, I would not use it to say hello to someone on the side of the road as the ground shakes when it is pressed. Watch out Belgian drivers!