charging xj gremlins

[ebock112]

ok im having some charging problems on my xj100 i want to see if you guys can help. ok my bike has been dying after about riding about 80 miles i checked the voltage on the battery after i recharged it read about 13.15 volts i put the meter across it rev the engine it goes up to about 13.5. but when i take it out ride it for about a half an hour i check the voltage again its at about 12.15 on the meter rev the engine goes up to about 12.5. i checked the resistance between the 3 white wires 0.4/0.5 ohms so those are in specs. the brown and green wire get about 6 ohms which its suppose to be at like 3.5. i pulled the cover off and ran the ohms across the two copper rings on the rotor and it was at 4.1 ohms. then i pulled out the field coil to see if maybe one of the wires from the brush came lose but they seemed to be good. when i checked the voltage of the brown wire with the key on it read 12 volts, on the green wire it read 0.5 and when i started the bike and ran it the voltage just stayed constant it did not go up to 9 to 11 volts. also the last time i ran the bike i notice the 3 white wires were getting pretty hot only after running it for about 5 mintues i was wondering if anyone could help me with this

[3Phase]

Ebock,

With the ignition switch on, does a feeler gauge or a small metal screwdriver get pulled against the right side engine cover at the alternator? If it doesn't, the field coil isn't working.

If the field coil seems to be working, test the alternator and the voltage regulator/rectifier.

With the regulator/rectifier connected normally, put a probe/paperclip in the back of the harness connector and ground the Green wire. That will bypass the voltage regulator section of the regulator/rectifier and run the alternator full field with unregulated output.

Start the engine, then check the voltage between the Red and the Black wires in the regulator/rectifier harness connector to see if it comes up to 14 - 16 volts or more as you raise the engine speed to about 3 or 4 thousand RPM.

If it the voltage goes up you need a new regulator/rectifier.

While you're testing, even if the voltage doesn't go up, check the voltage at the battery to make sure it's within 1/2 volt of the voltage measured at the regulator/rectifier. If the voltage at the battery is lower than the regulator/rectifier there is corrosion or a loose connection somewhere between the two.

[cywelchjr]

I'd also recommend doing the tests outlined in the manual for testing the voltage regulator as it sounds like you might have a bad regulator, you certainly have a non-working charging system, and the stator coils sound like they are good so it's probably either the field coil, wires or connections or the regulator. Make sure the connections are clean and tight, do the tests that 3phase suggests and do the regulator tests to see if the diodes test good or bad.

[Jerry]

Your XJ may need new brushes. The XJ alternator uses a brush design instead of the brushless design of the XS11s. Manual recommends changing the brushes regularly.

From a previous thread:
**********
Quote:
ALTERNATOR BRUSH
For 3-phase alternator systems Must reuse old terminals Fits XJ1100
$5.00US EA.

Part#24-2050
(http://www.partsnmore.com/)

BikeBandit has them close to Yamarobber's prices :

Quote:
5: BRUSH 1 43649-001 $29.03
6: BRUSH 2 47357-001 $29.03
*************
I just sent parts and more an e-mail to see if they still had them, BikeBandit now lists them at about $62.00 each.

One cross reference (BikeBandit) had the same brushes fitting a 1983 Yamaha 650. If so, MikesXS has these:

Alternator Brush Set - Fits: 1980-84 XS650. Complete set as shown. Replace
brushes if carbon brush is 7mm. (0.276") or less.
Part #24-2651
$16.50 USD per set.

http://www.mikesxs.net/products-29.html#products

If you buy from Mike's DON'T tell them is is for an XJ1100...they sometimes get a little persnickity about selling parts for other bikes, depending on who you talk to.