Yamaha F150B Service Manual

Also see for F150B: Owner's manual Service manual Owner's manual

7-55Power unitPOWRChecking the piston ring groove1. Measure the piston ring grooves.Replace the piston and connecting rodassembly if out of specification.Checking the piston ring sideclearance1. Measure the piston ring side clearance.Replace the piston and connecting rodassembly, piston ring set if out of specifi-cation.Checking the connecting rod big endside clearance1. Measure the connecting rod big end sideclearance a.Checking the crankshaft1. Measure the crankshaft journal diametera, crankpin diameter b, and crankpinwidth c. Replace the crankshaft if out ofspecification.Piston ring end gap a:Top ring:0.15–0.30 mm (0.0059–0.0118 in)Second ring:0.30–0.45 mm (0.0118–0.0177 in)Oil ring:0.15–0.60 mm (0.0059–0.0236 in)Measuring point b:20 mm (0.8 in)Piston ring groove:Top ring a:1.23–1.25 mm (0.0484–0.0492 in)Second ring b:1.22–1.24 mm (0.0480–0.0488 in)Oil ring c:2.51–2.53 mm (0.0988–0.0996 in)abcabcPiston ring side clearance:Top ring a:0.04–0.08 mm (0.0016–0.0031 in)Second ring b:0.03–0.07 mm (0.0012–0.0028 in)Oil ring c:0.04–0.13 mm (0.0016–0.0051 in)Connecting rod big endside clearance a (reference data):0.14–0.31 mm (0.006–0.012 in)aa