Assembly Guide

VALVE LIFTER
PUNCH MARKS
CAMSHAFT
EXHAUST VALVE
INTAKE VALVE
VALVE GUIDE (2)
VALVE SPRING (2)
VALVE SPRING RETAINER
VALVE ROTATOR (Exhaust valve only)
NOTICE:
If the valve rotator is not installed, the
exhaust valve may drop into the cylinder
when starting the engine.
CYLINDER HEAD
ROCKER ARM
PIVOT LOCK NUT (2)
10 N·m (1.0 kgf·m, 7 lbf·ft)
ROCKER ARM PIVOT (2)
PUSH ROD (2)
REASSEMBLY:
Check both ends for wear,
and check the rod for
straightness.
Be sure the rod ends are
firmly seated in the lifters.
ROCKER ARM (2)
REASSEMBLY:
Before installing, check for wear on the surfaces which contact
the pivot bolt, the push rod, and the rocker arm pivot.
ROCKER ARM PIVOT BOLT (2) 24 N·m (2.4 kgf·m, 17 lbf·ft)
VALVE STEM SEAL (Intake valve only)
INTAKE VALVE
REASSEMBLY:
· Do not interchange with the exhaust valve.
Valve head diameter: Intake: 25 mm (0.98 in) Exhaust: 24 mm (0.94 in)
· Be careful not to damage the valve stem seal when installing.
GASKET
DOWEL PINS
8 x 55 (4) (GX120), 8 x 60 (4) (GX160/GX200)
24 N·m (2.4 kgf·m, 17 lbf·ft)
REMOVAL/INSTALLATION:
Loosen and tighten the
bolts in a crisscross pattern
in 2-3 steps.
MARKING
TOP RING (CHROME FACED)
PISTON
PISTON PIN
PISTON PIN CLIP
REASSEMBLY:
Install by setting one end of the clip in
the piston groove, holding the other
end with long-nosed pliers, and
rotating the clip in.
Do not align the end gap of the clip
with the cutout in the piston pin bore.
CLIP
CONNECTING
ROD
REASSEMBLY: Install the
connecting rod with the
long end toward the
triangle-marked side of
the piston.
REASSEMBLY:
· Install all rings with the markings facing upward.
· Be sure that the top and second rings are not interchanged.
· Check that the rings rotate smoothly after installation.
· Space the piston ring end gaps 120 degrees apart, and
do not align the gaps with the piston pin bore.
· Space the oil ring side rail end gaps at least 10 mm (0.4 in)
apart. Coat the oil ring with oil after assembly.
SECOND RING (BLACK FACED)
OIL RING (COMBINATION RINGS)
PISTON RING
PISTON
PISTON
CRANKCASE COVER/CRANKSHAFT/PISTON
CYLINDER HEAD/VALVES
GX120 ·GX160 ·GX200 Engine Assembly Information
REASSEMBLY:
Install with the
triangle mark
toward the
pushrod hole.
REASSEMBLY:
Push in until the bearing touches
the crankcase. Be careful not to
damage the oil seal.
CONNECTING ROD BOLT
12 N·m (1.2 kgf·m, 9 lbf·ft)
6 x 28 (GX120)
12 N·m (1.2 kgf·m, 9 lbf·ft)
8 x 32 (GX160/GX200)
24 N·m (2.4 kgf·m, 17 lbf·ft)
CRANKCASE COVER
CRANKCASE
CRANKSHAFT
CONNECTING ROD CAP
REASSEMBLY:
・With the crankshaft in place, align the
timing punch mark on the cam gear with
the punch mark on the crankshaft gear.
・Before installing, inspect for worn and
weakened springs and check that the
decompressor weight moves smoothly.
TIMING GEAR
REASSEMBLY:
Install the lifters
immediately before
installing the camshaft.
TRIANGLE MARK
PUSH ROD HOLE
PUNCH MARKS
CUT-OUT
OIL SEAL 22 x 35 x 6 mm (GX120)
25 x 41 x 6 mm
(GX160/GX200)
GREAS
OIL SEAL
22 x 41 x 6 mm (GX120)
25 x 41 x 6 mm (GX160/GX200)
GREAS
BALL
BEARING
REASSEMBLY:
Install with the oil dipper toward the camshaft and the
ribs on the cap and connecting rod are aligned.
© Honda Motor Co., Ltd. 2009
SECOND RING
(BLACK FACED)
OIL RING
(COMBINATION RINGS)
TOP RING
(CHROME FACED)
GOVERNOR DRIVE
GEAR
CRANKCASE
COVER
GASKET
Do not reuse.
DISASSEMBLY:
Push down and slide the retainer to the side, so the valve
stem slips through the hole at the side of the retainer.
REASSEMBLY:
The exhaust valve retainer has a larger center recess than
the intake valve retainer so it can accept the valve rotator.
NOTICE:
Do not remove the valve spring retainers while the cylinder
head is installed, or the valves will drop into the cylinder.
REASSEMBLY:
・Before installation, remove carbon deposits
and inspect the valve.
・Do not interchange with the intake valve.
VALVE HEAD DIAMETER
GX120: IN: 22 mm (0.87 in)
EX: 19 mm (0.75 in)
GX160: IN: 25 mm (0.98 in)
EX: 24 mm (0.94 in)
CYLINDER HEAD
CYLINDER BARREL
Do not reuse.
OIL DRAIN
BOLT
18 N·m
(1.8 kgf·m,
13 lbf·ft)
DRAIN BOLT WASHER
Replace.
GX120/GX160:
GX200:
Refer to the above for information not shown below.
Replace with a new one
when reassembling.
GOVERNOR
REMOVAL/INSTALLATION:
· Before installation, remove any carbon deposits
from the combustion chamber and inspect the
valve seats.
· Measure the cylinder compression after reassembly.
CYLINDER HEAD
O-RING
OIL LEVEL SWITCH
6 x 12 (2)
REASSEMBLY:
The lock pin must be
installed with the
straight side of the pin
against the groove in
the shaft.
LOCK PIN
GOVERNOR
A
RM SHAFT
10 mm NUT
WASHER (2)
REASSEMBLY: Be sure
to install the governor
weight before installing
the crankshaft.
WASHER
REASSEMBLY:
Install inside
the case.
GOVERNOR WEIGHT
CLIP
GOVERNOR SLIDER
REASSEMBLY:
Insert firmly
into the shaft
groove.
REASSEMBLY: Install firmly in the groove.
Yellow ( To engine switch)
Green ( To side plate)
See the shop manual for additional information.