2004 Official factory service manual for Yamaha YFZ450S ATV Quad., Page 87Get this manual
CHECKING THE IGNITION TIMING CHECKING THE ENGINE OIL LEVEL 4Check: ignition timing
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aWarm up the engine and keep it at the specified speedEngine speed 1,7501,850 rmin bRemove the timing mark accessing screw 1cVisually check the stationary pointer to verify it is within the required firing range indicated on the A.Cmagneto rotorIncorrect firing range Check the pulser coil assemblydInstall the timing mark accessing screwLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLL