Forum

[pphilpot]

Hi all – I have a 1991 350 Bullet and the other day I realised that the headlamp bulb was dead, as was the rear lamp and one of the pilot bulbs. I replaced the rear bulb, but left the other two as I don't have spares yet. I took the bike out yesterday and after about 1/2 mile the amp meter went crazy (waving between fully positive and fully negative) and it spluttered to a halt after blowing the fuse. I walked it home and took a look, and found a snagged pilot lamp wire that I must have snagged when looking at the headlamp bulb. I fixed that, and thought that it may have been shorting out and blown the fuse. This morning I went to take it for a test run, and it started well, ticked over perfectly and the amp meter was stable. I left the lights off, and moved off down the road from home. Within 50 yards, and as the revs crept up the amp meter went crazy again, and so I stopped and then the bike cut out. Walked it back home, and the fuse has blown again.

Before I start trying to fathom the electrics, has anybody had experience of the amp meter behaving like this, and then blowing the one-and-only fuse?

Many thanks in advance

Paul

[scotty]

Hi I had similar prob turned out the wiring harness from tail light assy was shorting to earth where it comes through the front of the rear guard, when you .rewired it with a bit of 5 core trailer wiringused back brake blew fuse to get home took the linkage off the rear brake light switch.rewired it with a bit of 5 core trailer flex.all good put grommet in rear guard cheap in electronic stores.

[Gwilly]

Think Scotty hits the nail, sounds like a short in the brake light cable..

Touch the brakes and pop..

[pphilpot]

Thanks so far. So to start tracing the fault, I just measured the battery while ticking over the first time it gave me 12.5V - when I increased the revs slightly it blew the fuse. So I replaced the fuse and tried again. This time it gave me 13.6V at the battery and the 15V at increased revs (not by much though). After 5 seconds or so the fuse blew. Before this increase in revs I turned the lights on and off, the indicators, tried the horn and the brakes, no fluctuating ammeter, and the fuse was fine.

[pphilpot]

And here it is ticking over while I switch things on and off. With the revs increased it doesn't blow on this one, but it did afterwards...




https://www.youtube.com/watch?v=YZHZCcl ... e=youtu.be

[Gwilly]

15 volts dc is fine, sounds like its charging ok. carry out tests with engine off and ignition on, less distraction..

Sit on bike off stand and watch ampmeter.. Try turning handlebars lock to lock.. Then bounce the back shocks keep watching the meter..

You could replace the fuse with a headlight bulb/crocodile clipped, save wasting fuses..

[pphilpot]

Thanks Gwilly. I've done that and the seat is off too, so that I can get to all of the wires/connections. I've had the rear light lens off too to extract the wiring/connectors there. I've also worked with the wiring inside the headlamp. for the past hour not one fuse has blown. This is difficult.



It did cut out twice while idling (very unusual on this bike), and a small carb stutter (backfire through the air filter) which cut the engine. It never does when warm (only on a failed cold start).



I clutching at straws here now, but could it be anything to do with ignition – points and condenser? What symptoms do they show when they are misbehaving?



I guess I'll put it back together and take it for a run around the estate and see what it does.



Any ideas are thankfully received!



Many thanks again, Paul.

[pphilpot]

For the moment it is solved. In testing every connection, I must have secured one. I took it for a fast run for 10 minutes so it had a good rattle and shake and it didn't cut out. It did backfire once, which is very unusual, so maybe something still lurking with ignition perhaps.

Thanks for the suggestions guys.