My 2009 KLX250SF with 9800 miles on it will not charge high enough to maintain the battery. BUT WAIT before you tell me it needs a regulator rectifier... these are the tests it passed:
-Tested it with THREE different regulator rectifiers, one known working from another KLX250SF
-Tested regulator rectifier diodes according to service manual
-Tested with two different fully charged and not fully charged Yuasa batteries
-Disconnected heated grips and USB charger and checked for draw, 1.5 milliamps
-Stator resistance is 1.0 ohm across all three leads
-Stator output is over 70V (I think they're all around 46 at 5k rpms) and will rev to 100+
-Added a second ground
-Replaced battery to ground cable
-Checked power and resistance through starter relay and ignition switch
-Bypassed starter relay and ignition switch part of harness
-Swapped stator anyway, no difference in any measurement
-Extremely low or zero resistance through all of the stator plugs/pins to the wiring harness
-Low/no resistance from black/yellow RR ground wire to ground
The bike charges at idle at 13.7 volts and when you rev it, it drops to 12.3-12.5v. So it seems like the magnets have some pull when the bike is idling but as you rev it, they are too weak to produce sufficient output even though stator output seems fine? This is the only element of the charging system that I haven't replaced yet. I have one from a different KLX 250 so that may be my next step.
Someone suggested measuring AC voltage across the battery while the bike is running, but what would that tell me? I removed the LEDs from my brake light and that made no difference. I unplugged my headlight and that made no difference. It should be charging at 14.2-15.2 and where it's at right now is not enough to maintain the battery.
WHAT GIVES?!?!?!!?
