I've been outfitting my '92 GS bike for long travels through booney land.
I picked up some of the "Extra Loud" dual electric Fiam horns. Contrary
to what I've heard over the net, I only paid $22.00. At Western Auto
(an auto chain around IL and other places), they sell single Fiam horns for
around $11.00. The Dual extra loud ones go for $22. I forgot the price
of the air horns which come with a 12V electric compressor and either
1, 2 or 3 air horns that connect to the compressor with some clear vinyl
tubing. I seem to remember them being in the $30-$40 range.
Installation of the dual horns was pretty simple. The stock horn has a
3 layered sheet metal bracket which bolts onto the frame. I removed the
stock horn and bracket at the frame. The fiam "extra loud" horn
set comes with two mounting brackets which I then attached to each horn.
The fiam horns don't fit where the old horn went since the frame hole is
recessed, so I had to do some creative mounting. I picked up an 8mmx60?mm
bolt and three 8mm nuts + lock washers at the local hardware store.
I mounted the bolt in the frame where the stock horn mounted on such that
the bolt was protruding outward. I then used the two remaining nuts to
hold the ends of the two brackets in place at the end of the bolt.
Looks something like this:
_/O where '\' and '/' are the brackets \O 'O' is a horn and '-' is the 60mm bolt.
Note: Be sure the horns are situated such that when the front wheel shocks
give it doesn't hit the horns.
'91 and later R100GS, R80GS, R100R come with a horn relay which
seems to work fine with the fiam dual horns. The stock horn has two leads
"brown is ground" and green-gray isn't :-) The two leads are crampon
shielded female leads. Using my crampon kit from radio shack, some spare
18 gauge wire I had lying around and shielded crampons (also available
from radio shack), I fashioned a green-gray Y horn harness which attaches
to the positive terminals of each horn and plugs into the the existing
positive terminal from the bike's harness. The horns that come in the
"extra loud" kit pick up ground through the mounting bolt. Since
the frame is painted, it doesn't conduct real well unless some paint
is scraped off. Rather than do this, I made a male-crampon-to-
brown-lead-to-O-crampon that connected the bike's harnesses ground lead to
one of the horn mounting bracket screws.
As advertised, the horns are "extra loud". However, they don't sound like
a truck or freight train. Images of an early 70's big american boat type
car pop into my head when I hear them. Total cost is $25 + 1/2 hour of work.