Is there a way to bypass the voltage regulator on an 82 XS400?

[Ebola Monkey]

I've been fighting through this charging system problem on my wife's bike, and it's driving me nuts.

I found on some 650 forums that you can bypass the voltage regulator to find out if it's the problem.

Is there a way to do this on the 400's?

I've tried 2 different voltage regulators, 2 different rectifiers, and am ready to try different armatures, and field coils.

[drewpy]

no idea, tried google?

[Speedshop]

Not sure what they mean here. The regulator EARTHS the field winding. It should get the full battery voltage on the windings via the brown wire.

If the windings are not even getting full battery voltage there's a fault in the wiring.

If you shorted the green wire to earth then you'd effectively be calling for full power from the alternator.

Be careful, alternators are 100% rated so will run quite happily supplying an extremely high current also running it unregulated will very soon burn it out. Shorting the green to earth will put the system in a dangerous state.

I take it the regulator is earthed? (black wire should do this)

[Ebola Monkey]

That's what I was getting at speedshop. Trying to bypass regulator to eliminate it as the problem.

Here's what I'm getting with the field coil connected, and ignition on (still disassembled so not grounded via the case right?).

11.87V across battery

11.87V between GREEN from Coil, and Battery negative with the regulator disconnected.

2.50V between GREEN from Coil, and Battery negative with the regulator connected.

11.87V between BLACK from Coil, and Battery negative with the regulator disconnected.(same readings between the ignition, signal, and headlight fuses and battery neg, as they all tie into the same brown wire)

11.07v between BLACK from Coil, and Battery negative with the regulator connected.(same readings between the ignition, signal, and headlight fuses and battery neg, as they all tie into the same brown wire)

[Speedshop]

I must admit this is a tricky one. If you are getting the battery voltage at the windings and appearing on the earth side of the regulator thats got to be OK.

11.87 volts from a new battery is very low (13.8 is more like it) , can you get access to another battery? Does the terminal voltage jump up when you disconnect it from the bike's electrics? A car battery slaved in place of the bike battery would do.

Very unscientific, but with the ignition on will the generator just about have enough magnetism to hold a 10mm spanner against the case?

Lets stand back and have a cup of tea (of coffee). The items in the system are: the regulator/rectifier unit. The field windings. The output windings. The wiring. The battery.

The fault lies with one of these! Sherlock Holmes said rule out the impossible, then you must consider the unlikely. If the generator windings bell out OK these must be good. You've inspected the wiring. So really we need to look at the unlikely - the battery and the possibility you have two duff regulator/rectifier units.

I have known good spare XS650 regulator/rectifiers that could be slaved in and would work the same way as the 400 one.

[Ebola Monkey]

I must admit this is a tricky one. If you are getting the battery voltage at the windings and appearing on the earth side of the regulator thats got to be OK.

11.87 volts from a new battery is very low (13.8 is more like it) , can you get access to another battery? Does the terminal voltage jump up when you disconnect it from the bike's electrics? A car battery slaved in place of the bike battery would do.

Very unscientific, but with the ignition on will the generator just about have enough magnetism to hold a 10mm spanner against the case?

Lets stand back and have a cup of tea (of coffee). The items in the system are: the regulator/rectifier unit. The field windings. The output windings. The wiring. The battery.

The fault lies with one of these! Sherlock Holmes said rule out the impossible, then you must consider the unlikely. If the generator windings bell out OK these must be good. You've inspected the wiring. So really we need to look at the unlikely - the battery and the possibility you have two duff regulator/rectifier units.

I have known good spare XS650 regulator/rectifiers that could be slaved in and would work the same way as the 400 one.

It's SO low at the moment because I had been tinkering around with it so much after I pulled the generator. Now I'm delayed for a few days waiting on the new gasket to come in. I should have the new gasket Monday, at which point I'm going to reinstall the old generator (with some heat shrink around the chafed area), add a second ground strap to the chassis (for good luck), replace the faulty plug cap (assuming it comes in), charge up the battery, and cross my fingers.