Yamaha YZF-R1B 2012 Service Manual

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Contents

VALVES AND VALVE SPRINGS5-33TIPFor the best lapping results, lightly tap thevalve seat while rotating the valve back andforth between your hands.e. Apply a fine lapping compound to the valveface and repeat the above steps.f. After every lapping procedure, be sure toclean off all of the lapping compound fromthe valve face and valve seat.g. Apply Mechanic’s blueing dye (Dykem) “b”onto the valve face.h. Install the valve into the cylinder head.i. Press the valve through the valve guideand onto the valve seat to make a clearimpression.j. Measure the valve seat width “c” again. Ifthe valve seat width is out of specification,reface and lap the valve seat.▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲EAS24310CHECKING THE VALVE SPRINGSThe following procedure applies to all of thevalve springs.1. Measure:• Valve spring free length “a”Out of specification → Replace the valvespring.2. Measure:• Compressed valve spring force “a”Out of specification → Replace the valvespring.Valve spring free lengthFree length (intake)39.33 mm (1.55 in)Limit37.36 mm (1.47 in)Free length (exhaust)37.96 mm (1.49 in)Limit36.06 mm (1.42 in)Installed compression springforce (intake)187.00–215.00 N (19.07–21.92kgf, 42.04–48.33 lbf)Installed compression springforce (exhaust)185.00–213.00 N (18.86–21.72kgf, 41.59–47.88 lbf)Installed length (intake)34.50 mm (1.36 in)Installed length (exhaust)33.00 mm (1.30 in)Manuals by Motomatrix / www.motomatrix.co.uk / The Solution For Lost Motorcycle Coded Keysemail: info@motomatrix.co.uk