Fuel

• Lack of fuel or contaminated gasoline can cause the Raptor 350's engine to stall, misfire or fail to start. If more fuel is needed, refill the tank with fresh, unmixed and unleaded gasoline only.
  
  

Compression

• Lack of adequate compression can also cause problems when trying to start the Raptor 350. To test compression levels, access and remove the spark plug and use a compression gauge to test for compression levels in the Raptor's single cylinder. The owner's manual contains information on how to access and remove the spark plug.
  
  

Ignition

• Problems with the ignition system and spark plug itself can also prevent the Raptor from running correctly. Ensure that the spark plug is undamaged, that it is an NGK DR8EA plug as recommended by Yamaha, and that the spark plug gap is set between 0.024 and 0.028 inches. The Raptor's manual also includes Specifics on how to troubleshoot the spark plugs.
  
  

Battery

• A discharged or damaged battery is another common problem to explore while troubleshooting the Raptor 350. This quad takes a 12 volt, 8.6 ampere-hour battery.