I’ve spent my fair share of time scouring the small ads in local papers and poring over the MCN classifieds, trying to find that one special bike that’s right for me - low mileage, never been thrashed and good all round bargain. You may have been lucky enough to find one yourself. If so, did it occur to you that having coughed up the money and got your bike safely home, there was something more to be done if you’re looking forward to a long and happy relationship.
I’m talking about security, theft prevention, harder than steel locks and better than alarm systems. Well, it didn’t occur to me, and the nicest looking Guzzi Le Mans I’d seen in a long time was stolen within a week. It had almost certainly been hot wired. I left the Guzzi for less than five minutes in a town centre car park, protected, so I thought, by its steering lock, but when I returned it was gone. Although we're well advised to use shackle type locks such as the Kryptonite or Sentinal, few of us can really be bothered if we’re just nipping down the shops for a few cans of lager or something for the weekend. And of course, it’s during those few minutes that the opportunist thief will strike.
A steering lock will rarely hold him back. The earlier type can often be snapped off by just jerking the bars, while later models usually require the wielding of an iron bar. Alternatively. a screwdriver jammed into the lock usually works. The system I’m going to describe is ideally suited to stopping the kind of character who expects to hot wire the bike and be off down the street in less than half a minute. The system won’t cost much more than a fiver, it’s dead simple to wire up and easy to use.
There’s no fiddling about with trembler adjusters and alarm keys, the whole system is activated by the mere flick of a concealed switch. It’s so quick and easy to use that you'll be able to guard against hot wiring every single time you leave the bike. Anyone trying to ride off on the machine will find the alarm sounds when the ignition is turned on and the engine is impossible to start.
A minor caution, if your bike is still under warranty, it could be invalidated by cutting wires. Always double check before cutting and joining wires - mating the wrong wires together could easily cause an electrical fire or wreck sophisticated electronics found on newer machines. All joints should be made by twisting the wires together for a couple of turns then carefully soldering and wrapping with insulation tape. Make sure everything is waterproofed - the idea is to stop thieves riding the bike, not the owner.
The trickiest part is deciding where to put the DPDT switch. It could go under a locking seat or, my favourite, in the rear light housing. The switch should be positioned where it’s easy to use and the thief won't spot it. Under every seat or tank there’s a space where the horn can be placed. If it’s not possible to bolt it down, a few cable ties will work alright. Just make sure it’s not going to do any damage by rubbing against the paintwork or chafing wires.
The easiest way to wire up the circuit is to consider it as two separate systems, the immobiliser circuit and the alarm circuit, each of which connects to opposite sides of the switch. First, the immobiliser. Identify the wires connected to the handlebar kill switch, either by checking the colour code in the manual or removing the switch and looking at the wires. Trace this back to the wiring loom or connector. Cut one of the wires from the kill switch at a point where thieves can’t easily see what you’ve done. The bike should not run once the wire is cut. If there’s no kill switch, cut one of the wires on the low tension side of the coil. Wire up to the DPDT switch as shown.
For the alarm circuit the horn should have a good earth connection. Run a wire with a ting terminal or washer soldered to the lead from one of the horn terminals to a bolt on the frame. The other wire comes from the live power supply to the horn switch. Again, this can be found from either looking up the colour code or tracing wires. Test the wire by connecting it up to the horn before it’s connected to the DPDT switch the horn should sound. Tap into the live wire and wire up the circuit as shown. And that’s all there is to it.
With the DPDT switch in its off position everything should work as if the switch was not connected up - the engine will run and all the normal electrical equipment can be operated. With the ignition turned off and the DPDT switch turned on, the bike will sit there looking innocent. If the ignition is turned on or someone tries to hot wire the bike it'll be impossible to start and the concealed horn will sound.
A last word on waterproofing - build silicone grease compound on the back of the DPDT switch to keep water out. Don’t forget, that someone can still wheel your bike away, so there’s still no substitute for a good shackle lock; if you can be bothered to use it.
Malcolm Ingham