How to Troubleshoot Yamaha ATV Charging Problems

Riding a Yamaha ATV for extended periods of time might cause electrical problems from overuse. Our 2009 Yamaha YFZ450R wasn't charging and couldn't maintain battery voltage after a weekend out on the track, so we popped it open and performed some simple diagnostic tests. 

Watch the video above and follow the steps below to learn how to diagnose and troubleshoot Yamaha ATV charging system problems.

Tools and Parts - Troubleshooting Yamaha ATV Charging Problems

  • Phillips screwdriver
  • Ratchet and extension
  • 5mm Allen
  • 10mm socket

Buy Yamaha ATV stator

Buy Yamaha ATV regulator-rectifier

Checking Yamaha YFZ-450R Charging Problems

Step 1. Pop the seat off, disconnect the battery, and connect a volt/ohm meter to the battery's terminals. Next, set the meter to DC volts. The volt/ohm meter should have a voltage reading of 12.5 volts or higher. 

Yamaha ATV charging problems test

Yamaha YFZ450R volt/ohm test

Step 2. Disconnect the multimeter from the battery, and reconnect the battery to the ATV, then start it and let it idle. Next, reconnect the voltage multimeter to the battery while it's running and look for the reading to increase to 14 volts or higher.  If the voltage meter shows a decrease in voltage or no increase in voltage after firing it up, it means the electrical system is not charging, and the next step is to test the stator, which is located on the lower left side of the machine. 

Yamaha YFZ450 electrical problems troubleshoot

Step 3. Unplug the stator and take a resistance measurement across each winding with the voltage meter set to ohms. It should measure between .32 and .48 ohms. Any measurement lower than .32 means you need to buy a new stator. Take the same measurement on the stator in AC voltage, which should read between 35 and 40 volts. Anything less than 35 also means the stator needs to be replaced. 

Yamaha YFZ450 stator test

Yamaha ATV electrical system diagnostics

If the stator test produces enough voltage, the next step is to pull the front panel off the ATV to check the voltage on the regulator-rectifier.

Yamaha YFZ450R electrical problem diagnostics

Step 4. Unplug the charging circuits of the regulator-rectifier that go back to the battery, which are the red and black wires on the top, to expose the regulator-rectifiers terminals. 

Yamaha YFZ450R regulator/rectifier test

Step 5. Set the volt/ohm meter to DC voltage before connecting it to the regulator-rectifier's terminals, and look for a voltage reading of approximately 12.5 volts. If the multimeter registers anything less than 12.5 volts, you need to buy a new regulator-rectifier.

Yamaha ATV electrical diagnosis tests

NOTE: If the regulator-rectifier tests well for a good voltage measurement but the electrical system is still not charging,Yamaha recommends replacing the regulator-rectifier anyway. Move on to Step 6 only if you bought a new regulator-rectifier. 

Step 6. Hook up the volt/ohm meter to the new regulator-rectifier, then  connect the rectifier to the machine. The ATV should start up with the new regulator-rectifier installed, and the voltage reading should be approximately 12.5 volts. 

Yamaha YFZ450 ATV regulator-rectifier test

Step 7. Tighten the 10mm bolts that hold the new regulator-rectifier in place, and replace the front panel and the seat.  

Yamaha YFZ450R regulator rectifier installation

If testing and replacing the stator and/or regulator-rectifier don't resolve your Yamaha YFZ450R charging problems, or the ATV just won't start at all, watch the video below to see how to check Yamaha ATV starting problems







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