I had intermittent partial loss of electrical power last night while on the way home. The oil/neutral lights would go very dim and the engine could barely keep running spluttering away at idle speed, no reaction to throttle. Yanking on the loom would occasionally get the power back.

This is what I found the next day:

- battery at 12V and would not charge to higher voltage.
- rectifier connectors were very corroded, cleaned that up
- the resistance between the alternator wires was 0.6, 0.6 and 0.9 ohm which is nominal
- my earths are fine, earth upgrade was recently installed and I cleaned up all the connectors except for the rectifiers
- battery and rectifier were replaced a year ago
- wiring loom is in a bad condition
- measured the resistances of the rectifier and they are all nominal except between the yellow(alternator) connectors where the resistance was infinite (spec is 30k-500k ohm)
- strange thing was that when I recharged the battery (still only 12V on the terminals) and started the bike I actually measured a lover voltage on at a higher rpm: 14V@1200rpm and 13V@4500rpm at the battery terminals.

What to do next? I don't want to start randomly replacing parts and hoping a bad component won't break them.

The rectifier is type sh693-12

What actually is the earth upgrade kit?

magg wrote:What actually is the earth upgrade kit?

Connecting various earth points by separate wires instead of the frame.

Could you be more specific, which points are connected to where exactly. IMO the minimum earth connection upgrade is the addition of a direct link between the -ve battery terminal and the chassis. The OEM design does not appear to have one, does your bike have such a connection?

Measure the voltage directly at the output terminals of the rect/reg, do you get a reliable 14.0 - 14.5 volts at this point.

magg wrote:Could you be more specific, which points are connected to where exactly. IMO the minimum earth connection upgrade is the addition of a direct link between the -ve battery terminal and the chassis. The OEM design does not appear to have one, does your bike have such a connection?

Measure the voltage directly at the output terminals of the rect/reg, do you get a reliable 14.0 - 14.5 volts at this point.

Earth wires from frame earth point to coils, starter motor and the regulator.

Main worry is why are my voltages at the battery decrease as the engine speed increases, it should be the other way around!

When you say you have added an earth from from the rect/reg does this mean you have spliced into the -ve lead of the rect/reg?

magg wrote:When you say you have added an earth from from the rect/reg does this mean you have spliced into the -ve lead of the rect/reg?

From the mounting screw of the regulator.

Unless the heat sink of the rect/reg is internally connected to the -ve terminal of the rect/reg, your lead from the mounting screw to chassis services no purpose.

To check, you need to remove the rect/reg from your bike and measure the resistance between the metal heat sink and the the rect/reg -ve output terminal.

Have you measure the output voltage at the +ve and -ve output terminals of the rect/reg, do not disconnect the rect/reg.

krisztian_andre wrote:

magg wrote:Could you be more specific, which points are connected to where exactly. IMO the minimum earth connection upgrade is the addition of a direct link between the -ve battery terminal and the chassis. The OEM design does not appear to have one, does your bike have such a connection?

Measure the voltage directly at the output terminals of the rect/reg, do you get a reliable 14.0 - 14.5 volts at this point.

Earth wires from frame earth point to coils, starter motor and the regulator.

Main worry is why are my voltages at the battery decrease as the engine speed increases, it should be the other way around!

It sounds like your regulator and or genny is broken.

Have you done electrical tests on it yet? There simple standard tests to get the output of the bike.