The second modification is the adding of an air horn to sound more like a vehicle you should MOVE for, rather than like a road runner cartoon you should ignore IF you actually heard it!! Meep-Meep! Impressive, ahuh, I'de move! Sure I would.
The original horn can be gotten at most auto stores like Kragen;s, but the chrome "bling" one in the last picture (and on the 8th day, God created Chrome!) is the Bad Boy Air Horn (actually the catalog says "Bad Boy Air orn", their pell specker is worse than mine!), part # 360-110.
Here is a picture of the original horn mounting.
This is a couple of views of the mounting bracket.
And here is a shot of the female spade lugs to the original horn that we will unhook, and reuse later. (shown in diagram below)
This metal bracket is from a short piece of 1/8" x 1" mild steel. I bent it in a vise so that there is a 90 degree twist, and then a bend (sharp bend here to facilitate missing the tank lower edge) so the long piece extends for mounting the horn assy. Leave it longer than you think you need on both ends and cut off after fitting the holes to make a better looking fit. Ah, yeah, about those "extra" holes... You might want to sorta disregard those. I goofed and hate to waste material, so redrilled a couple smaller ones in the right place. The middle one is the "spare"! The bottom one wouldn't be elongated with a file if I could actually measure! OR, actually if I could wait for daylight instead of measuring it by flashlight! Patience is NOT my greatest attribute! There are a several angles and shots to show the final bends that fit best.
Then here is the raw bracket during first fit check, which if you have more patience or skills than I do (and most have) you wouldn't be checking it, you would be mostly done by now. The bracket is cut to final size here. Now here are all the pieces used.
I used stainless hex head bolts and nylon lock nuts, with the toothed washers to prevent any movement due to vibration. Then we have several shots showing the horn assy and relay mounted on the bracket.
YES, you have to use a relay. The current, while short, is LARGE to run the compressor. The shot of the relay shows where the pin numbers are. The diagram is actually provided with the horn assy. It is shown below. There seems to be some confusion as to what relay to use so I am adding this relay drawing to make it easier to see how it works, and type. I also edited the wiring diagram to show the pin numbers and make it a little clearer. Hope this helps.
Then we have a closeup of the painting of the bracket to enthrall those easily amused, and after that, a closeup of the lock nut holding the assy to the bracket.
Normally, the horn assy mounts to a bolt head coming in horizontally to that U shaped cutout, but that would not hold up to the vibes on a bike well, so we used the top. I did drill out the hole slightly and used a larger bolt that provided better holding power, though a 1/4" x 20 is perfectly adequate. (that is what is actually shown here, but I later changed out the horn assy for an all chorme unit from jpcycles.com - shown in last picture, after this initial installation was road tested through many miles and potholes, and the new one had a too small hole size. If your going to drill out bigger anyway, why just go a little ways?) Here is the first on-bike fit check of the whole assy.
It comes pretty close to the tank, so I made that top bend pretty tight, but after two months of use on all kinds of roads, vibrations, etc., I haven't had any problems with it hitting the tank. Not even after a few real good potholes. Though there IS a small piece of rubber cemented on top where it WOULD contact the tank seam, IF it were to) The 1/8" steel seems to be plenty sturdy enough to prevent bending from the weight of the horn assy, but absorbs small vibrations well. 1000+ miles and nothing has lossened, though periodic checking of ALL fasteners is recommended. You will notice there really isn't any way to "hide" a unit this size on the bike, there simply isn't any "extra" room anywhere. Here it isn't terribly intrusive, and from all views, shows not too bad a look.
I ran all the wires up under the tank and tied them with tie wraps to keep them out of the way. I wired the unit through a fuse directly to the battery, as shown here.
I don't like to "splice" into wires if I don't have to. If they carry any amount of current (and this horn uses upwards of 8-9 amps) it weakens the wires capability to not overheat when carrying the rated current for that size wire. For small load wires, it isn't any big deal. (beside, I used to run an Electrical R&D department for a while and have a phobia about derating cables!) There you have our second easy mod, and it really gets a cager's attention. No "meep, meep", but 158db of truck air horn that brings their heads around and YOU into focus!! The first time I got crowded towards the side of the road by some lady that evidently thought I was invisible, I just pressed it once and she almost went into the highway median, two lanes AWAY from me! I don't agree (not totally) that loud pipes save lives, but I already have a couple of proofs that loud HORNS do!!
Here is a picture of the final installation after I succumbed to the "chrome fetish" devil and swapped out the original shown in the mod for one from jpcycles.com! The original was $59.95 at Kragens, and the chrome jobby from jbcycles was $69.95. The chrome one look MANY more gooder!
NEWS FLASH!! Kurt Theoret, one of our readers (without whom there would be no reason for this site, I ALREADY know what I did!) found the Stebel chrome air horn on http://www.bikerhiway.com/ (part # SNH-02) for $41.95!! Thanks, Kurt!!