ST1100 Electrics

ST1100 P1 C04 After

The first bit of electrical work I did on the bike was on the original conversion to naked form. The front fairing subframe had brackets for various relays and the ignition control unit (ICU). Having scrapped the (bent) subframe, the relays went behind the headstock, sharing space and bracket mountings with the ignition coils. The ICU went on a now-redundant subframe mounting bracket. None of this required any wiring changes, though I did pull out nearly a kilo of wire and a few relays that were not actually doing anything – probably a failed attempt at hazard warning lights. The new indicators were just connected up to the original wiring with chocolate-block connectors – one is visible as a bulge in the wire behind the horn.

With a more radical re-style, a bit more electrical surgery was needed to move components around.

For reasons best known to Honda, the indicator relay was behind the right side panel but all the wiring goes to the front of the bike, so it made sense to me to relocate it. This was just a matter of stripping the outer cover off that part of the wiring loom, putting the relay on the front of the airbox. For neatness sake I shortened the wires – just cut a chunk out of each, slipped on a short length of heat-shrink insulation, solder together.

The fuse box was to be moved from behind the back of the left side cover, to the top of the airbox, as was the ICU. In this picture the fuse box (red wires attached) is resting on top of the under-seat fuel tank on its journey north.

ST1100 P4 E06 Electrics

As you can see above, a lot of the wires were tangled round each other in the loom, necessitating more cutting and joining before the fuse box could be re-homed. Most of the wires to the fuse box come from the front of the bike and needed to be shortened, but a few come from the back and needed to be lengthened. Fortunately I have a cardboard box full of old bits of bike wiring – I can’t remember quite where or when I acquired most of it. To extend wires is the same process as shortening them, except for splicing in an extra bit, preferably of the same or similar colour, though not always possible. I prefer to keep both ends in the original colour and have a different colour in the middle if necessary. All the joints are soldered – it’s worth learning the art. I found I needed a 40 watt soldering iron to cope with the cold in the garage.

Here the wire-extending is done, wire shortening not yet done. For now, all that spare wire is wrapped round the top of the airbox, and it might stay that way for a while. It looks horribly complicated, but by dealing with one wire at a time it’s not difficult.

ST1100 P4 E08 Electrics

The fuse box actually ended up where the ICU had been, on the left of the airbox, with a vague notion that it might be more accessible there.

With the battery now further from the starter relay it needed a longer red ‘live’ lead. I un-soldered the terminals for the relay and battery connections from the original wire and soldered them onto a length cut from a set of old jump leads. It needed a blow-torch to supply enough heat. It was comforting to know that old Pan Europeans are being broken for spares all the time, just in case I lost or destroyed any vital component. The black ‘earth’ lead was already long enough.

ST1100 P4 E10 Electrics

The only other significant bit of electrical work is replacing the old warning lights with an LED panel – covered under ST1100 Lights, Clocks & Fairing

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