What's it mean?

I'm very uneducated when it comes to mechanics. One thing I noticed last night when I was putting the bike away was that if I rev the engine, the lights on the instrument cluster get brighter, especially the high beam indicator. What's it mean, if anything?

mikeg

 

Means that your charging system is working correctly.
they don't really put out much at idle. once you get the rpm's up a bit, they wake up. that's the nature of spinning a magnet in a coil of wire (or vice versa) faster = more current.

 

That just means that your current load at idle was more than the altenator could put out. The altenators of our bikes deliver their peak power at around 5500 RPM. In your case at idle, the high beam light along with all the other lights was drawing current from your battery so there was a net loss in electricity from your battery.

The one thing that you could do is go through your bike's electrical connections and make sure they are clean (without the white powdery oxide layer) since that will cause a resistance to current flow. The other thing would be to test (or have tested) your altenator output. There should be a good description as to how to do that here somewhere or someone else will chime in.

 

well it works like this:
The bike is equipped with a dynamo,

Typically a dynamo gives a higher voltage when turning faster (compare with a dynamo on a bicycle, the faster you ride, the brighter the headlight will shine)

When revving up the engine, the dynamo turns faster, giving more voltage.

The AC is converted by a diodebridge to DC which feeds the battery and all equipment.

Measuring Voltage after the regulator (the diode bridge) there can be a voltage of 14-18 Volts DC.

edit: wow i'm slow

 

Agreed.

One VERY important thing, though, is to check that it doesn't crank the voltage up TOO high. I had that problem on my CBR 600. Turns out the stock voltage regulators on the older models were known to fail in this way.

For the XJ, you can check like this:

a) start the bike
b) put a voltmeter across the battery terminals (I really do recommend waiting until AFTER the bike is started to do this)
c) rev the engine slow-ish up to about 4500 and let it fall.

The voltage across the battery should never rise about 15V and should never fall below 12V (12.5 or so, really).

If it goes above 15V, you have a bad voltage regulator AND YOU SHOULD REPLACE IT BEFORE IT FRIES YOUR TCI. I got lucky on my Honda. It started popping high-beam bulbs, and I got right onto the problem before it made things worse. Good thing I did.

If it drops below 12V, you have two problems. Your charging system isn't working (bad rectifier and/or alternator brushes too short) AND your battery may be shot. Put the battery on a charger, check the brushes, check the diodes in the reg/rect., and try again.

... Wow. I must have learned something reading all this stuff. ;p