Yamaha's Warrior-series ATVs operate on a magneto-based generator to power its ignition and lighting systems. An electrical current is generated as a permanently-magnetized steel rotor is rotated by the Warrior's crankshaft past a coil of copper wires called a stator. Although the stator is fairly robust, its wire coil can be damaged from excessive heat or lack of proper maintenance. Once the coil is broken, the magneto will not be able to produce sufficient power to allow the Warrior to run. Replacing the stator and the rotor, if needed, is a fairly quick task that can be completed in an hour.
Things You'll Need
- Socket wrench
- 17 mm socket
- Oil pan
- Torque wrench
- 5 mm Allen wrench
- Stator coil
- Magneto rotor
- Yamaha flywheel puller (Yamaha part # YM-0414)
- 2.6 quarts of SAE 10W30 motor oil
Start your Warrior's motor and let it idle for three to five minutes to warm up the crankcase oil. Stop the motor and let it cool for another 10 minutes. Unscrew the drain plug from the bottom of the motor's crankcase, using a socket wrench and a 17 mm socket. Drain the crankcase oil into an oil pan, then tighten the drain plug to 31 foot-pounds with a torque wrench and your 17 mm socket.
Unscrew the bolts from the round crankcase cover on the left side of the motor, using a 5 mm Allen wrench. Pull the cover and its gasket away from the motor.
Unbolt the stator and pickup coils from the inside of the left crankcase cover, using a 5 mm Allen wrench. Pull the pickup coil off of the cover and away from the stator coil. Pull the stator coil off of the cover, then follow its wiring to the wiring harness under the left side your Warrior's seat rails. Unplug the stator from the wiring harness.
Place a new stator coil into the left crankcase cover, then remount the pickup coil into its original position. Tighten the pickup and stator coils' bolts to 7.2 foot-pounds with a torque wrench and a 5 mm Allen wrench. Route the stator's wiring through the channel cut into the bottom of the crankcase cover.
Pull the magneto rotor off of the motor's crankshaft with a Yamaha flywheel puller. Do not remove the starter clutch from the crankshaft. Slide a new magneto rotor onto the crankshaft, aligning the notch cut into the center of the rotor with the woodruff key protruding from the starter clutch. Skip this step if you are only replacing the stator coil.
Place the left crankcase over and a new gasket onto the left side of the motor. Tighten the cover's bolts to 7.2 foot-pounds with a torque wrench and a 5 mm Allen wrench. Plug the stator coil's wiring into the Warrior's wiring harness under the left seat rail.
Take the dipstick of of the right crankcase cover and place a funnel into the cover's filler neck. Fill the motor's crankcase with 2.6 quarts of SAE 10W30 motor oil.
- "The Professional Motorcycle Repair Program"; Professional Career Development Institute; 1995
- "Yamaha YFM350X Warrior Service Manual"; Yamaha Motor Corp.; 1997
- "Yamaha YFM350XC Warrior Supplemental Service Manual"; Yamaha Motor Corp.; 1998
- Photo Credit Jupiterimages/Photos.com/Getty Images
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