2012 wr450 regulator/rectifier

My 2012 WR450 has the baja designs DS kit installed, has approx 10k street miles and ~ 500 dirt miles on it. Last tuesday as I was riding home from work, the check engine light came on and about 10 seconds later the bike died. I checked the oil level to make sure it was not do to low oil pressure and the level was fine. Attempted to start it and it kick started but immediately died. Tried to start it again and no lights and the fuel pump did not spin up. After getting the bike home, I jumped started the bike and started right up and took the jumper cables off and measured the voltage and it was 7.3 volts(with bike running) at the battery which indicated to me that the rectifier/regulator assembly was not working charging the battery and the bike eventually died. So I ordered a new rectifier/regulator assy and put the battery on my charger and when fully charged was reading 12.7 volts. Maintained it on a trickle charge till the new assy arrived. Installed the new assy and battery. Started right up and measured the voltage at the terminals with the bike running and it read 12.9 volts. Rode the bike to work and home yesterday no problems whatsoever. On the ride in to work this morning and the exact same thing happened as last tuesday. I live in western washington and it has ranged from 20 - 40 degrees over the last month. Have had no problems till last tuesday. I have not checked the stator output yet.


1. Anyone else had any similiar problems like this?


2. Could the battery have been damaged by being discharged down to 7.3 volts that it caused the new rectifier/regulator assy to fail in a day? 


3. Anyone with any thoughts on what to check before I have to take it in to a dealer and spend $$$ to troubleshoot an electrical gremlin.



Edited by Grover9876

If your battery dropped to 7.3V it may have been damaged to the point where it won't hold/take a charge. Try replacing the battery.


Have you measured the voltage output at the terminals since the second failure? A bad battery should not damage the charging system.

Edited by woods-rider

I would get the battery checked first... Not sure if the battery is the cause or a symptom, but it would be good to know if it is good. 


My WR has the same BD kit and I had a LOT of fun getting the charging system working after I did the upgrade. But since you have 10k miles on it I doubt you have the same problem I had.

Update on some troubleshooting I did tonight. Checked the resistance of the stator and within spec as stated in the owners service manual. Had similiar voltages pin to pin from the stator with the bike running 31.4 to 31.6 at idle and 45 at ~5000 rpm. The owner's service manual states a spec for the AC magneto as "standard output     14.0 V, 160W @ 5000 rpm". Did some research on youtube and watched some videos on stator troubleshooting and all of those videos show voltages around 45V at idle up to 65V at 5000 rpm. Granted those were all streetbikes but shouldn't the stator on our bikes put voltages like that? Disconnected the output wire from the rectifier/reg assy and the battery side connector read battery voltage and rect/reg side connector read 0.71V (spec should be 14.1-14.9 no load). i knew the rectifier was bad but should that only last ~30 miles?


Any thoughts greatly appreciated.

I believe you have another, different problem that may have taken out the new RR you just installed.


Something is shorted, causing the RR current to increase to the point where RRs are being popped, or... it's the weakened battery causing excessive charging current.


I think you're in for at least another RR, and possibly a battery.  You shoudl also be looking for shorts within the wiring, with the ohmmeter.  Just cause the DS kit was installed and lased this long, does not mean something with it (or something else) has gone "south".



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