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[Mark B]

It's a 1999 home market 500 Bullet with Boyer ignition and powerbox. I noticed at the weekend that the ammeter seemed a bit sluggish and today, on the way to get a new MOT, the engine died when I indicated to turn left. Realising it was probably the battery at fault (it was new 18 months ago), I tried the headlight and only got the faintest glimmer. So, the battery is on charge and the Bullet's sulking by a roundabout a few miles away. My other bikes are Italian, so I've never had electrical problems (ahem...) Any advice on what to check and in what order? Thanks for any suggestions, Mark.

[Gwilly]

Damn thats bad luck, hope the bike will be ok being left..

Perhaps the first thing to check are the connections on the yellow wires from the power box.

These are the charging wires, follow them down to where they will be connected into the wires from the alternator, check these connections are clean and tight.

If ok then you should use a multimeter to check voltage is being produced across these yellow wires when the engine is started.

Depends on what alternator is fitted for that year as they changed type, 3 wire DC to 4 wire ACDC but should get 20-40VAC..

Check earth/ground connections frame to battery and black wire from power box..

If all checks out ok then check for parasitic drain with ignition off but thats a long way off yet, hopefully just a loose connection..

[Gwilly]

Then of course it could be the ammeter itself or its connections, also the ignition switch internals..

Think i should of just read the paper and enjoyed a cup of tea

[Adrian]

As the headlamp is powered by the battery that suggests it's a three wire alternator, all DC lighting, I think 1999 was the changeover year to 4 wires and AC headlights.



One thing I'd check, after loose wires and dodgy connections/earths, is whether the battery still holds its charge, new 18 months ago is sadly no guarantee now. After that the reg/rectifier.


A.

[Mark B]

Thanks Gwilly and Adrian, that'll keep me busy this weekend. After a couple of hours charging the battery yesterday, I recovered the bike (strangely nobody had decided to nick it); it started OK and I got home safely and very very wet.

[ric]

If the output from the alternator wires is unequal check for 360* stator/rotor clearance.

[ric]

If the output from the alternator wires is unequal check for 360* stator/rotor clearance.

[Mark B]

I put the battery on charge and checked it the next day: 12.3 volts across terminals, 11.9v with the engine ticking over, rising to 13.00 with some revs. Battery to earth also reads 12.3v.

The 3-wire alternator had some very second-hand looking spade connectors so I replaced those, and the connectors to the powerbox are clean and tight.

I went for a test ride today and it ran fine although some information about the ammeter reading would be helpful (as someone posted yesterday, some of us have to ask the most obvious-sounding questions, and I've never had a bike with an ammeter before...) The ammeter needle dips as it should when going over compression when starting, but while riding today it never went above dead centre on the dial, while being ever-so-slightly in the red on tick-over. I put the headlight on while I was riding and the ammeter needle went straight to the bottom of the red zone. I kept the headlight on for about 10 minutes until I got home at the end of a 1/2 hour ride. Checking the battery again it still read 12.3v, so hadn't lost any charge during that time.

Does this suggest that it is now charging properly, or does the negative ammeter reading with the headlight on mean that it's not?

Thanks for any thoughts from the experienced ones here! Mark.

[ric]

Your ammeter is like a bank manager. When in the Red it's telling you you're taking more out than you're putting back. Something needs to change so your electricity account stays in the Black during riding, even with the lights on, otherwise the bike will eventually stop running.

The occasional dip into the red when you add a temporary load such as indicators,horn or brake light is fine but a permanent discharge needs investigation.

[Exile]

I had a similar problem after I fitted a GPS on my bullet. For some strange reason it proved to be the straw that broke the camels back. I had the impression that the alternator was at its maximum running the bike and the GPS was the culprit. We have to drive with lights on permanently over here in Denmark. If I switched the GPS off, the battery held its charge.


A high output alternator fixed all this.... available from our hosts.