Yamaha 55DEHD Service Manual page 86

POWR
Power unit ..................................................................................................... 5-1
Checking the compression pressure ....................................................... 5-1
Removing the power unit ......................................................................... 5-9
Removing the flywheel magnet ............................................................. 5-11
Removing the electrical component ...................................................... 5-11
Removing the control lever and throttle cam ......................................... 5-12
Intake manifold ........................................................................................... 5-13
Removing the reed valve assembly ....................................................... 5-14
Checking the reed valve ........................................................................ 5-14
Cylinder head, exhaust cover ................................................................... 5-15
Removing the cylinder head .................................................................. 5-18
Checking the cylinder head ................................................................... 5-19
Removing the exhaust cover ................................................................. 5-19
Checking the exhaust cover ................................................................... 5-20
Checking the PCV .................................................................................. 5-20
Crankcase ................................................................................................... 5-21
Removing the crankcase ....................................................................... 5-24
Removing the piston, connecting rod assembly
and crankshaft assembly ..................................................................... 5-24
Checking the cylinder block ................................................................... 5-25
Disassembling the piston and connecting rod assembly ...................... 5-25
Checking the bearing ............................................................................ 5-25
Checking the piston pin ......................................................................... 5-25
Disassembling the crankshaft ................................................................ 5-26
Checking the cylinder bore .................................................................... 5-26
Checking the piston diameter ................................................................ 5-27
Checking the piston ring side clearance ............................................... 5-27
Checking the piston pin boss bore ........................................................ 5-27
Checking the piston ring ........................................................................ 5-27
Checking the crankshaft ........................................................................ 5-28
Checking the connecting rod big end side clearance ........................... 5-28
Checking the connecting rod small end axial play ................................ 5-29
Disassembling the upper bearing .......................................................... 5-29
Assembling the upper bearing ............................................................... 5-29
Assembling the crankshaft .................................................................... 5-30
Assembling the piston and connecting rod assembly ........................... 5-30
Power unit
6885J11