03 WR250F voltage regulator problems

Mudd Slinger

N. Texas SP
May 5, 2004
I have a 03 Yamaha WR250F that gets ridden about 2-4 times a month. It looks at if I just lost the voltage regulator for the second time. My easy button quit working and I found my battery voltage low on a riding trip. I charged the battery a couples of hours and started troubleshooting. When I started up the bike for the 1st time after the trip, I found the regulator at the connectors under the tank putting out ~15 volt. Seemed a little high. I went back to the battery and the voltage started jumping around. I shut down the bike and checked the fuse and battery connections and all seemed OK. I started the the bike again and was only seeing around 8+ volts at the battery. I shut it down again and went back to the regulator connectors and it was now about 8 volts. I checked the winding and seen around 0.5 ohms on lowest resoultion meter scale (a little high) but considering the meter probally acceptable. I started checking all the related connectors and did a little troubleshooting with the ohm meter with the schematic in hand and did not see any problems.

This is the second regulator to go out. Replacing the regulator the 1st time fixed the charging issues but this is only a couple of rides later (~ 10 hrs) and it went again.

Has anybody had similiar problems or learned anything about the charging system on the Yamaha thumpers that might help.

The battery will still still return to 13+ volts after charging.
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