© Honda Motor Co., Ltd. Power Product Service Division.

GXR120

CARBURETOR

PISTON DISASSEMBLY/REASSEMBLY CAM PULLEY

VALVE CLEARANCEValve clearance inspection and adjustment must be performed with the engine cold.

Insert a feeler gauge between the valve adjusting screw and the valve to measure valve clearance.

Top dead center of the compression stroke is the point where the cutoutin the starter pulley (i.e. opposite side from the mark on the flywheel) is inalignment with the lower bolt hole of the fan cover.

VALVE CLEARANCE 0.15 ± 0.04 mm (IN) 0.20 ± 0.04 mm (EX)

FEELERGAUGE

VALVE ADJUSUTINGSCREW

VALVE ADJUSUTINGSCREW

VALVE ADJUSUTINGLOCK NUT

VALVECLEARANCE

TIMINGBELT

ALIGNMENT MARKS

HEAD COVER MATING SURFACE

IDLE SPEED ADJUSTMENT

INSTALLATION

TOP RING

SECOND RING

OIL RING

CUT OUT

CLIP

120°

120° 120°

Install all rings with the markings facing up.Space the piston ring end gaps 120° apart.

MAKER MARK"2N" MARK

MAKER MARK"N" MARK

IGNITION COILIGNITION COIL AIR GAP INSPECTION

FLYWHEEL

IGNITION COIL

Primary side resistance value

0.75－0.95Ω 6.1－9.3 kΩSecondary side resistance value

PRIMARY SIDE SECONDARY SIDE

0.2-0.5 mm 0.2-0.5 mm

2

2

3

3

4

4

5

5

8

9

9

8

20mmSIDE RAILSPACERSIDE RAIL

Do not align the end gapof the clip with the cutoutin the piston pin bore.

Set the piston top dead center of the compression stroke (both valve fully closed). Top dead center of the compression strokeis the point where the cutout in the starterpulley (i.e. opposite side from the mark onthe flywheel) is in alignment with the lowerbolt hole of the fan cover.

Align the alignment marks on the cam pulley so that they are in line with the head cover mating surface.Be careful ta avoid turning the crankshaftwhen installing.

ENGINE STOP SWITCHINSPECTION

Attach the tester leads to the black wire and the ground plate of the engine stop switch,and check for continuity.

Switch OFF position : There should be continuity.

Switch ON position : There should be no continuity.

6ENGINE STOP SWITCH

GROUND PLATE

7.5 N･m

YELLOW

YELLOW

BODY

BODY

BLACKBLACK-

0.5-10kΩ

+

∞ ∞

∞∞

OIL ALERTINSPECTION

7

7

0.5-10kΩ

S2ZDJ400en

Do not reuse

Do not reuse

Do not reuse

Do not reuse Do not reuse

Do not reuse

Exchange

Exchange

Do not reuse

Do not reuse

Do not reuse

Gasoline is highly flammable and explosive. Confirmno leaks are present in fuel system parts.

WARNING

3 N･m

5.5 N･m

5.5 N･m

1 N･m

9.8 N･m

7.5 N･m

7.5 N･m

18 N･m

64 N･m

2.3 N･m

2.3 N･m

FLOAT TYPE

FLOATLESS TYPETHROTTLE STOP SCREW

THROTTLE STOP SCREW

・Start the engine and allow it warm up to normal operating temperature.・ With the engine idling, turn the throttle stop screw in or out to obtain the standard idle speed.

Standard idle speed

1,850±150 min (rpm)-1

REMOVAL INSTALLATION

FLOATLESS TYPEFLOAT TYPE

GOVERNOR1) Move the control lever to the "FAST" position.

2) Loosen the governor arm nut on the governor arm.

3) Push the governor arm end toward the carburetor side, and open the carburetor throttle valve fully.

4) Holding the carburetor throttle valve fully open, turn the governor arm shaft clockwise fully, and tighten the governor arm nut.

5) Check to see whether the governor arm and the carburetor throttIe valve operate smoothly.

6) Start the engine and allow it to warm up to the normal operatlng temperature. Move the control lever to the maximum engine speed position and check the maximum engine speed.

7) Adjust the maximum engine speed, if necessaiy, by loosening the lock nut and turning the adjusting bolt in or out.

the lock nut securely.

1ADJUSTMENT

Maximum engine speed (no load)

4,100 ±100 min-1 (rpm)

8) After adjustment, tighten

THROTTLE STOPSCREW

THROTTLE STOPSCREW

CLEANNING Clean the body and passege by spraying carburettor cleaner before installation.

MAIN JE

Install in the direction shown

Install in the direction shownT

MAIN JETDo not reuse.

Do not reuse.

Do not reuse.

Do not reuse.

Do not reuse.

Do not reuse.

Do not reuse.

Do not reuse.

Do not reuse.

Cleaning

Cleaning

Remove carbon deposits by lightly tapping the outerflange with a plastic hammer before installation.

THROTTLE VALVE

GOVERNOR ARM

CONTROLLEVER

GOVERNORARM SHAFT

GOVERNORARM NUT

ADJUSTINGLOCK NUTBOLT

FAN COVERALIGNMENT MARK

STARTER PULLEY

CUT OUTBOLT HOLE

FAN COVERALIGNMENT MARK

STARTERPULLEY

CUT OUTBOLT HOLE

YELLOW

BLACK

BODY

　

Spark plug gap

RecommendedSpark plug

0.6 - 0.7 mm

NGKDENSO

CR5HSBU16FSR-UB

SPARK PLUG

Engine oil capacity 0.28 L　(0.3 mUS qt,0.25 lmp qt)

ENGINE OIL

SAE 10W-30API Service Classification SE or higher

Recommended oil

ThreeBond 1207B or equivalent・ Assemble within 10 minutes after applyingthe liquid gasket.・ Wait for 20 minutes after assembly. Do notadd oil or start the engine during this period.

LIQUID GASKET HEAD COVERCYLINDER BARREL

FUEL TUBECheck the fuel tubefor deterioration,cracks and gasolineleakage.

Check the fuel tubefor deterioration,cracks and gasolineleakage.

FUEL TUBE