Charging System

The bike seemed to charge OK, but the lights were dim at idle. They brightened up with a rev, which made be think that the stator and regulator were doing their job but the battery was weak.

At idle voltage was just 12 volts, but above 5,000 it climbed lethargically to 13.8. Within specs, but not very impressive. After a few days of charging the battery wouldn't give more than 12.2 volts, which is pretty low.

These bikes are known for having weak charging systems, though, so I wanted to head such problems off before they appear in the future, without spending a fortune. Since it was down for the engine work, I figured I'd do a little creative re-wiring.

The problems are many, but they come down to a marginal-sized stator, over-use (mis-use?) of bullet connectors, one stator phase (of three) that's completely unregulated and a regulator that's not efficiently grounded to the battery.

I formulated a plan to upgrade the weak spots of the stock system:

- Marginal stator: This I couldn't do much about - I measured the resistance of the stock one and it seemed fine. Looked fine too, when I pulled off the cover.

- Sub-optimal bullet connectors: I replaced all connectors with 1/4-inch spade terminals

- One unregulated stator phase: I replaced the separate rectifier and 2-phase regulator with a modern unit (from a Honda CBR929rr) that will control all three phases instead of just two. I wired the third phase directly to the regulator instead of through the lighting switch (and a bunch of bullet connectors).

- Poor rectifier/regulator wiring and design: I wired the regulator directly to battery instead of through the harness. The GS originally has a separate rectifier and regulator, which just adds resistance to the circuit. The 929 combined rectifier/regulator had two positive and two negative outputs - I ran one positive and one negative directly to the battery. The second positive went to the wiring harness like the stock regulator and the second negative was grounded to the starter solenoid along with the harness negative wire.

I took the opportunity to do some more cleaning of the battery box area. I also removed and painted the electrical panel for more bling. And finally, I replaced the weak battery with a nice new 12N14 battery from Wal Mart.

Now, even though the new regulator is about double the size of the old one, you can't tell. Looks good, doesn't it?

That should cure my electrical and charging problems for the forseeable future...