WR450 '06 Regulator / Rectifier problem

Hi everybody,

first, sorry for my poor english...

Here is the problem:

My WR's battery started to loose charge so I checked all that I could found on TT...

- Dissasemble and clean all conectors including the one behind the head light

- Charged the battery overnight (12.7 DC volts)

- Started the engine (12.6 DC volts revving it, so I assume

it isn't charging)

- Checked the charging coil voltage (24v AC idling, .6 ohm resistance, So I assumed it's ok)

- The bike doesn't blow up any bulbs and they are bright and stable, the headlight voltage is 12/13V AC idling and 9V AC when I rev it a little.

BTW The battery is a Yuasa brand new one, and it holds the charge perfectly.

All of this lead me to the conclusion that I have a fried regulator / rectifier....

So I called my local Yamaha dealer and they didn't have it in stock, they called the Yamaha importer in Buenos Aires, and they also didn't have it in stock... the delay to receive it from US is 5 months due to importation restrictions!!!!!

So, my cuestion is:

Wich regulator / rectifier from other bike can I adapt to it? There's a way to repair it? I have a two day ride in one month, and I would like to have my e-start and lights running OK....

Thanks to all in advance,

Diego from Argentina

The YFZ450 atv and the wr250 use the same regulator. The wires may need to lenghtened or shortened.

Can I use a 2007 and newer regulator ? They are of different shape, but have the same connectors...

Yes. Same regulator. Just a different housing.


i've found a YFZ450 r/r, it has the same wires colors but different connector (4 pins instead of 3) and the ground is inside the connector, so I dissasembled it and reassembled with my old 3 pin connector, with the ground appart (with insulation tape)

Now, the voltage of the battery is 12.4 volts with the bike stopped, after e-starting it, I have 12.20 volts and it goes up to 12.30 / 12.35 volts revving it.

I re-checked the charging coil voltage, as I doesn't have a precision multimeter to measure the impedance. I have to disconnect the coil with the bike running because it doesn't want to start with the coil disconnected, I have up to 60V AC in both wires revving the engine, so I assume the charging coil is OK.

Mounting back the old RR, i have 12.2 volts and it goes down to 9 volt when revving it ??????

Can anyone give me a clue of what's happening? Or my RR is burnt and the YFZ RR is different from my WR's RR ??

Many thanks in advance!!


Oh, I measured the impedance of the charging coil wires to ground, and it's 0.6 / 0.8 ohm with a very cheap multimeter... (200 ohm minimum scale)


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