Yamaha MT-03 Service Manual

Also see for MT-03: Owner's manual Owner's manual Owner's manual

5-23VALVES AND VALVE SPRINGS3. Eliminate:• Carbon deposits(from the valve face and valve seat)4. Check:• Valve facePitting/wear •Grind the valve face.• Valve stem endMushroom shape or diameter larger thanthe body of the valve stem → Replace thevalve.5. Measure:• Valve margin thickness “a”Out of specification → Replace the valve.Valve margin thickness0.80-1.20 mm(0.0315-0.0472 in)6. Measure:• Valve stem runoutOut of specification → Replace the valve.NOTE:• When installing a new valve, always replacethe valve guide.• If the valve is removed or replaced, always re-place the valve stem seal.Valve stem runout0.010 mm (0.0004 in)EAS00240CHECKING THE VALVE SEATSThe following procedure applies to all of thevalves and valve seats.1. Eliminate:• Carbon deposits(from the valve face and valve seat)2. Check:• Valve seatPitting/wear → Replace the cylinder head.3. Measure:• Valve seat width “a”Out of specification → Replace the cylinderhead.Valve seat widthIntake1.00-1.20 mm(0.0394-0.0472 in)Exhaust1.00-1.20 mm(0.0394-0.0472 in)▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼a. Apply Mechanic’s blueing dye (Dykem) ontothe valve face.b. Install the valve into the cylinder head.c. Press the valve through the valve guide andonto the valve seat to make a clear impres-sion.d. Measure the valve seat width.NOTE:Where the valve seat and valve face contactedone another, the blueing will have been re-moved.▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼