Yamaha MBK MW125 2014 Service Manual

VALVES AND VALVE SPRINGS5-22EAS30283REMOVING THE VALVESThe following procedure applies to all of thevalves and related components.TIPBefore removing the internal parts of the cylinderhead (e.g., valves, valve springs, valve seats),make sure the valves properly seal.1. Check:• Valve sealingLeakage at the valve seat → Check the valveface, valve seat, and valve seat width.Refer to “CHECKING THE VALVE SEATS”on page 5-24.▼▼▼▼ ▼ ▼▼▼▼ ▼ ▼▼▼▼ ▼ ▼▼▼▼ ▼ ▼▼▼▼ ▼ ▼▼▼▼ ▼▼▼a. Pour a clean solvent “a” into the intake andexhaust ports.b. Check that the valves properly seal.TIPThere should be no leakage at the valve seat “1”.▲▲▲▲ ▲ ▲▲▲▲ ▲ ▲▲▲▲ ▲ ▲▲▲▲ ▲ ▲▲▲▲ ▲ ▲▲▲▲ ▲▲▲2. Remove:• Valve cotters “1”TIPRemove the valve cotters by compressing thevalve spring with the valve spring compressorand the valve spring compressor attachment “2”.3. Remove:• Valve spring retainer “1”• Valve spring “2”• Valve “3”• Valve stem seal “4”• Valve spring seat “5”TIPIdentify the position of each part very carefully sothat it can be reinstalled in its original place.EAS30284CHECKING THE VALVES AND VALVEGUIDESThe following procedure applies to all of thevalves and valve guides.1. Measure:• Valve-stem-to-valve-guide clearanceOut of specification → Replace the valveguide.Valve spring compressor90890-04019Valve spring compressorYM-04019Valve spring compressor attach-ment90890-04108Valve spring compressor adapt-er 22 mmYM-04108• Valve-stem-to-valve-guide clearance =Valve guide inside diameter “a” -Valve stem diameter “b”1212435