How to make your electrics future proof

Published: 24 July 2016

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Just bought an old-ish bike? Here’s how to ward off electrical gremlins with a few simple tools

1. Understand the basic principle

Most people say electrics are a mystery. Well, imagine the cables as hosepipes. Instead of water flowing through them, it’s electrons. All you need to do is make sure they are free to flow. Corrosion, damage and bodgery restrict that flow – exactly like treading on a hosepipe. On an older bike, the results can be blown bulbs, burned cables or a dead regulator rectifier, which can take out the battery and stator too.

2. Unblock your reg rec

The regulator rectifier deals with the ‘raw’ electricity produced by your bike’s generator. Especially on an older bike, it should be connected as directly as possible to the battery. Often the connection goes ‘round the houses’ through the loom. Disconnect the battery, unplug the reg/rec, and use a needle to lift the plug’s plastic barb and extract the positive and negative spade connectors. This one’s pretty bad.

3. Now make your reg rec happy

Using the correct ‘W’ crimp tool and 33 amp cable, make new positive and negative connections directly to the battery, taking care that they are routed to avoid chafing or stretching. Heat-shrink the old connectors and cable tie them out of the way. The new positive cable needs a 30 amp inline fuse. You can get the new cables, fuse holder and connectors at kojaycat.co.uk

4. Renew your main earth

This is where current from the various electrical goings-on passes from the frame back to the battery. You can recognise it as a ring terminal bolted to the frame or engine casing. Unscrew it, inspect for corrosion and clean with a wire brush. Brush the casing or frame back to clean bare metal. Reassemble, tighten and paint with silicone grease. Repeat for the starter motor cables.

5. Lube the connector blocks

Next time you have the bodywork off and expose the connector blocks, pull them apart and peer inside. Green or white gunge means corrosion-related problems on the way. Extract the terminals if poss, clean with a soft wire brush and paint the entire thing with silicone grease to prevent corrosion. Otherwise, grease the mating faces of the plug halves.

6. Inspect for damage

Taking bodywork off is a good time to check cables aren’t rubbing. Detect and repair/renew any exposed copper strands, or old bodges using PVC tape, Scotchblocks or red pre-insulated connectors. On this ten year-old XT660R a patch of rust on the top frame tube is beginning to chafe these cables. If there’s any damage, solder in new cable and heat shrink the join.

7. Evict the alarm

Alarms can be a source of electrical trouble. To remove one, drill the siren speaker to shut it up, disentangle (but don’t cut) the various sensors from the bike, then open up where the alarm grafts into the central loom using a scalpel. Expose and de-solder the four or five alarm wire grafts, then rejoin the loom’s original cables using solder and heat shrink. Tape up.

8. Fit accessories properly

Pre-insulated connectors are cheap and widespread. They work on cars (sort of) but are useless on a bike. You can see why: exposed cable strands and a gaping hole for corrosion. Instead, order ‘W’ crimp connectors with separate insulators (about 25p a side), and a suitable crimp tool (about £10) from Vehicle Wiring Products (www.vehicle-wiring-products.eu) or Kojaycat.

9. See the difference?

Here’s a battery terminal for heated clothing that’s been crimped correctly. It will last years, and if you’re handy you can also solder it for extra conductivity. Don’t cut the rubber battery insulator to fit it in. Find a way to run it inside the insulator, above or below existing terminals. Use a washer if you need to space it out a bit. If necessary, push the cable through first, then crimp it.

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By MCN

The voice of motorcycling since 1955