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4-3-8 Cylinder head/valve train
1）Disassembly/reassembly：
① Disassemble recoil starter/housing； ② Disassemble fuel tank；
③ Disassemble ignition coil, flywheel； ④ Disassemble muffler；
⑤ Disassemble air cleaner； ⑥ Disassemble carburetor；
Finally, disassemble the cylinder head/valve train as shown on the above figure.
NOTICE:
Valve spring retainer：
Push down the valve spring and move the retainer to the side so that valve stem
slips through the side hole.
Do not remove the valve spring retainers while the cylinder head is attached to
the cylinder, or the valves will drop into the crankcase.
2）Inspect/ Service/ Repair：
①Valve stem outside diameter
Bolt M6×12（2 pcs）
Bolt M6×80（2 pcs）
Loosen and tighten the bolts in
a crisscross pattern ，
Especially when tightening, all
bolts should be tightened
gradually and evenly up to
specified torque.
Torque：8±2N.m。
Cylinder head
cover
Gasket
Lock nut
Bolt
Valve rocker
shaft
Rocker
Exhaust
rocker
Crankshaft
Camshaft spindle
Sealing ring
Timing chain guide
Chain
Tensioner
Spring
Pin
Stud M8
Stud
M6
Spark plug: Clean and adjust
spark plug before installation
Cylinder head ：Before installation,
remove any carbon deposits from
the combustion chamber, check
retainer contact
Gasket
Dowel —A type
（Φ10×14）
Bolt: Assembly ／disassembly：
Turn and tighten the bolts in a
crisscross pattern in 2 or 3 steps.
Torque: 26N.m
Spring retainer
Valve seal
Valve Spring
Exhaust valve Before
installation, remove
carbon deposits and
inspect the valve.
Intake valve
Don’t interchange with the
exhaust valve in assembling.
Intake mark IN
Exhaust mark EX
Be careful not to damage the
valve stem when installing.