Recently had an issue with my '12 wr450 where if I was to place the multimeter on the battery while the bike was running, it would show that the battery wasn't getting charged. Battery voltage would just count down like a clock until bike shut off from lack of battery power to run fuel pump. Battery was only 2 months old.
Went through and checked and cleaned all plugs and connections in the charging system, still nothing. Next I checked to see if I had proper voltage coming out of the stator. All was good, roughly 20v AC on idle and up to 70v AC giving it revs. Next was to check voltage output from regulator/rectifier, manual says should be getting 14+ v DC at 5000rpm, I was getting 1.5v DC. My theory, rec/reg had crapped itself.
Bought a brand new rec/reg from yamaha, fitted it up and I'm still getting around 1.1-1.5v out of the rec/reg. Damn. Back to a bit more head scratching and some more testing of other stuff.
When the stator is unplugged from the rec/reg, I'm getting 20v AC on idle and about 70v AC at 5000rpm on all three wires but when I plug the stator back into the rec/reg, that voltage drops back to 1.5v on those three wires. (I barked the three wires on the stator side of the plug to test that). I have checked the resistance of all three white wires coming out of the stator as per the manual and they test ok to me. (I'm no electrician though).
I have taken the stator into my local yamaha and they said there is nothing wrong with it, I then took it to another electricians shop in town and they also said it checks out OK.
Now I'm really at a loss as to what the problem is. Does anyone have any suggestions on what i could test/try or know what my problem is. It's doing my head in and I just want to go riding!
Maybe the stator is stuffed, but I don't want to waste $250 if i dont have to.