generator help

[cjcampo]

After 18 long months I've finally restored a greasy, crud encrusted 74 XLCH into a clean leak-free bike. But now I can't get the generator to charge the battery. I've got a new battery and voltage regulator. New field coils and brushes are on order. Wiring is good and clean and the generator indicating light is not grounded. I don't have the fancy tester to check the armature so I'm just hoping that the trouble is with the field coils. Anybody have experience with these 12 volt generators? What's the usual weak link in the system?

[motorhead1]

Did you polarize?

[JohnR]

Are the + & - nuts at the generator secure on there posts?

[cjcampo]

Yes to both. I polarized as per the H-D repair manual and according to the new voltage regulator instructions. All + and - terminal connections are clean and tight. Commutator segments have been polished clean and the commutator slots are cleaned out of any carbon build-up. Brushes look OK but I'm replacing them anyway. No wires inside the generator appear to be broken or insulation breached where wires could ground to the gen. housing.
Cliff

[Perry Ruiter]

In my experience the armature is far more likely to be the source of the problem than the field coils. How do you know it's not the regulator? Try this. Disconnect the F lead and jumper the F terminal to ground. Start the bike. Do you have a charge now (measuring voltage at the battery, the higher you rev the higher it should climb, but don't be a dummy about it)? Yes, the problem is in the regulator. No, jumper from battery + to the A terminal. Charge now? Problem is also in the regulator ... Perry

[cjcampo]

Perry,
I've done the first part of your procedure (that's in the repair manual) and only got about 2 volts revving it to about 2500 rpm. I did not do the second part of your procedure, I'll give it a try. I've checked the resistance between the armature commutator segments and the lamenant strips on the body of the armature to see if any of the winding insulation is breaking down. I found no ground. The book calls for checking these with a "growler". I guess this is some kind of megger tester like they use to check the integrity of motor windings. Using an ohm meter may not be a good enough check. The voltage regulator is brand new and hopefully good.
Cliff

[Perry Ruiter]

Here's a couple other things to check. First, with the generator off the bike, battery negative to a good ground on the generator, F terminal to a good ground on the generator and A terminal to battery positive. The generator should motor. If not you have a generator problem.
Second, in addition to checking that the commutator is isolated, you should also go around bar to bar and make sure everything checks out. Set your meter on ohms (it will be low ohms, around 1). Pick a starting point and put your probes on adjacent commutator bars. Check the reading. Now move both probes over one bar (so one probe is on a "new" bar and the other is on the bar the first probe was on). Repeat moving around bar by bar. The reading should be the same at each pair of bars. This will confirm that your slots are indeed clean and that you don't have a bad joint or broken wire in the armature... Perry

[cjcampo]

Finally found the trouble with the charging system. The ground wire from the voltage regulator was connected to a bad ground point on the engine crank case. Once the wire was connected to a good ground point I had plenty of juice. Battery staying at 12 plus volts. But now I blew the oil pump. Oil signal light came on. Checked rocker supply lines, no oil. I knew I should have put a new drive pin on the pump shaft when I rebuilt the engine. Maybe I shouldn't have painted the bike Lollipop Lime Green.
Cliff

[mmoore]

the first rule of motorcycle electrics (and electronics) is check your grounds. (I learned this the hard way long ago)