I hope you have understood the troubleshooting steps in Part 3. They're not difficult and they are how generations of successful career Honda mechanics have approached the problem. There is no more accurate and more conclusive method.

But there is another thing to think about. What if your battery has been going dead, and you've done the visual checks and have properly load-tested the battery, and the system's charge rate is correct--that is, 3 amps or more? What then?

There is another layer to charging system troubleshooting. It is centered around a test that measures the balance between the charging system and the bike's electrical loads. That is, the energy going into the battery compared with that going out of the battery. This is called the "breakeven" test.

Jack, select and connect your multimeter the same as for a charging amps test. Remember, the meter goes in-between the disconnected battery negative cable and the battery negative terminal. Just as with the charge test, temporarily hold the battery negative cable tight against the battery negative terminal when electric starting the engine. Or just kick start it. Once the engine will idle without the choke, very slowly increase engine rpm until the reading goes from discharge at idle to not yet charging. Equalibrium, in other words. Breakeven, mechanics call this. The meter is reading neither charge or discharge. It's in-between.

The CB500/550 and CB350F/400F charging systems breakeven at 1300 rpm when the headlight is not activated. When the headlight is on, the breakeven is slightly higher, but still no higher than 1700 rpm. If your result is higher than this, and you followed the troubleshooting method in the previous article, something on the loads side of the charging-versus-loads balance is out of balance. Even though the charging system is working properly, putting into the battery the right amount of energy, the electrical load on the system is excessive and is sucking up more than its share, leaving the battery with too little.

Look for things that are pulling down more energy than the bike was designed to handle. A more powerful headlight, faulty ignition coils, or loose or corroded electrical connectors. Very common sources of overload are a dirty engine kill switch, a dirty keyswitch, and a sticking or misadjusted brake light switch. Pinpoint and fix the problem and retest breakeven.

You pinpoint a bad switch or connector by doing a volt drop test across each suspect part. Multimeter jacked and selected for 12v, red test probe on the input side of the switch or connector, black on the output side, keyswitch and kill switch on. There should be no reading. Zero volts. On really old parts we can allow one to two tenths of a volt, but no more than that. It's supposed to be zero.

But what if none of those things are the problem? All the connectors and switches test good? Then we do a key-off test. Connect your multimeter similiar to doing a charge amps test, with three important differences. One, use the volts/ohms jack not the 10 amp jack. Two, select your neter for milliamps. Milliamps is labeled "mA" on your meter. And three, DO NOT TURN THE KEYSWITCH ON. We're looking for electricty that leaks out even when the bike is not being used. Simply read the meter.

None of the bikes we are talking about, the CB500/550 or the CB350 Four and CB400F, were factory equipped with any electrical component that would cause them to bleed electrical energy when the key is turned off. This would include a clock, a radio with memory presets, an alarm, GPS, an iPhone, etc. Therefore, there should be no mA reading. If you get one, you either have one of these items, or you have a leaking rectifier. If you do have one of these electrically "full-time" accessories, consider its contribution to your battery's discharge issue, especially if it draws more than 10mA.

But if there is no such extra load, then the problem is the rectifier. The rectifier is unique in that it is the only factory-supplied electrical part on the motorcycle that is hard-wired to the battery full-time, i.e. has no keyswitch control. A key-off discharge in the absence of any added accessories that can account for it is caused by a bad rectifier, one that is permitting backflow out of the battery. Replace the part and retest key-off discharge.