2012 WR450 Charging Issue


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.

Thanks, Brendan.

charging wires to ground should be open circuit - check if you got continiuty.

Common failure mode on the DRZ400, yet stator still puts out 70VAC with no load but as soon a  load is applied (ie battery) it all gets shorted to ground and battery doesn't charge

I did a few continuity tests, here are my findings.


Bike not running, stator plug not connected - no continuity to ground.

Bike not running, stator plug connected, rec/reg output not connected - no continuity to ground.

Bike not running, everything connected - no continuity

Bike running, everything connected - getting continuity from back of stator plug to ground.

Bike running, rec/reg output unplugged - no continuity


What does this tell you? Should there be continuity from the stator plug to ground when the bike is running?


Thanks for your help.



No continuity to ground ever on the charging wires as this indicates that the varnish on the wire used in the coils on the stator has / is breaking down and its shorting out to ground

They should have continuity between the charging wires (approx 1ohm) as this indicates that the coils are not burnt out


If these two conditions are meet then its prob not the stator

Hi brendan. What did you fix this problem in the end? I am having the exact same ussue now. I had a similar issue around a year ago and it was a bad earth on the plug under the fuel tank that has six wires going into it and a little metal plate. This time though i cant fix it. cheers

Well I have the same issue, Stator dead as, Ohms reading is .000, stopped with cable disconnected. No charge on the multimeter at idle or 5000rpm (on AC). Bike (WR450 2015) is only 2 years old so fairly disappointed about this. Also I see that nobody seems to make a replacement stator for these EFI bikes, why is that?. OEM parts make my wallet scream rape. Well that's bikes I guess, if anyone knows of a company making stators for these bikes please let me know.


No need to replace just have it rewound...cheaper that even an aftermarket stator

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