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[David]

Thanks chaps, if I go over ac circuit this weekend with a multimeter it should find any of the problems mentioned.

[David]

Hello guys, I have started the checks of my motorcycle electrical system today with the multimeter. The battery with engine off at idel, with engine on at 1500rpm, and 2000rpm is good. The alternator out put is very strong, going above 30+ volts upto 36 volts at high revs, I don't risk taking the revs any higher. When the engine was at high rpm and I turned the key to switch the engine off the bike kept running, but when the engine is at low rpm the engine will switch off via the key, is this normal behavior?

[David]

Right I started to conducted the AC system checks. Keeping the same engine speed. At slightly fast, idle alternator output reads 15 volts. When I checked the voltage at the headlight at same engine speed I got a reading of 8-10 volts. Is this normal?

[papasmurf]

What is the voltage at the headlight with the ignition turned on and the engine NOT running.

[David]

Papa the my bike is a 2004 Bullet 65. The head light is run directly from the alternator with an inline regulator. With the engine off it wouldn't give a reading would it?

[David]

Just ordered a new regulator, as in the Snidal manual, it says if the voltage is to low regulator is at volt, and Snidal says the voltage should be between 11-13 VAC from idle to 2000rpm . I guess 8-10 VAC is low...But I fail to see how it would cause my problem?

[papasmurf]

David as the headlight will work with the ignition on but with the engine not running you will be able to test the voltage.
(If it didn't stay on if you stalled the engine at night it would be somewhat of a serious safety hazard.)

[Gwilly]

David have you found the AC reg yet? Under the seat bolted to the cross member with the other reg/rec..

Should look like this





This reg is wired in parallel to this very simple circuit, US bikes don't even have an on/off switch, just the dip and flash..

It should be possible to easily eliminate the reg by simply disconnecting it from the circuit and running the motor up with headlight on.

Not too fast or you'll blow the bulb..

The reg will fail in two ways. 1/ it fails to trim the excess voltage above 15 VAC, thus blown bulb.

2/ It trims everything above 8 volts and dumps to earth, under voltage to bulb.

Don't think you'll find a fuse on a AC circuit as theres no positive and earth as in DC, you may however find on some machines a resister fitted as a safety device which will prevent too high a voltage being generated in the event of a bulb failure. i.e. the US bikes with permanent on headlight and no off switch..

[Dennis C]

Papasmurf, The headlight is AC and runs from the alternator and will go of if the engine is not running, just the side lights are DC and will stay on.

[David]

Yes I found the AC regulator! I mentioned the AC reg in my previous posts, with voltage readings. Please refer back Gwilly. I have ordered a new AC regulator. What you have described Gwilly is the very test Snidal mentions in his manual to test the AC regulator, unplug regulator if voltage rises, regulator is at fault, replace regulator.
I confused my starter relay for the ac regulator. Turns out my bike doesn't have the starter relay.
The AC regulator is placed behind my coil. To access the AC reg, I have to unplug the dc reg and rec, disconnect the wires going to the coil, and remove the coil. So no way of doing the test you and Snidal recommend. I will see if the problem persists with the new AC reg.