MAINTENANCE AND REPAIR INSTRUCTIONS

3.Remove the screw behind the engine cover (Fig. 41).

4.Disconnect the spark plug wire.

5.Clean dirt from around the spark plug. Remove the spark plug from the cylinder head by turning a 5/8 in. socket counterclockwise.

6.Remove the engine cover (Fig. 40).

7.Clean dirt from around the rocker arm cover. Remove the screw holding the rocker arm cover with a large flat blade screwdriver or Torx T- 25 bit (Fig. 42). Remove the rocker arm cover and gasket.

8.Pull the starter rope slowly to bring the piston to the top of its travel, (known as top dead center). Check that:

•The piston is at the top of its travel while looking in the spark plug hole (Fig. 42)

•Both rocker arms move freely, and both valves are closed

Screw

Fig. 41

Rocker

Arm

Cover

Spark

Plug

Hole

Fig. 42

Adjusting Nut

Rocker Arm

.003–.006 in.

(.076–.152 mm)

Feeler Gauge

Valve Stem

Fig. 44

 

• To decrease clearance, turn the adjusting nut

 

clockwise.

b. Recheck both clearances, and adjust as necessary.

11.

Reinstall the rocker arm cover using a new gasket. Torque

 

the screw to 20–30 in•lb (2.2–3.4 N•m).

12.

Reinstall the engine cover. Check alignment of the cover

 

before tightening the screws. Tighten screws.

13.

Reinstall the muffler cover. Slip the rear tab on the muffler

 

cover into the engine cover rear slot. Then slide the

 

remaining slots into the tabs until they snap into place

If these statements are not true, repeat this step.

9.Slide the feeler gauge between the rocker arm and the valve return spring. Measure the clearance between the valve stem and rocker arm (Fig. 43). Measure both the intake and exhaust valves.

 

(Fig. 39).

14.

Check the spark plug and reinstall. See Replacing the

 

Spark Plug.

15.

Replace the spark plug wire.

REPLACING THE SPARK PLUG

Adjusting Nuts

Rocker Arms

INTAKE

EXHAUST

Use a replacement part number 791-180852B spark plug. The correct air gap is 0.025 in. (0.655 mm.). Remove the plug after every 25 hours of operation and check its condition.

1.Stop the engine and allow it to cool. Grasp the plug wire firmly and pull the cap from the spark plug.

2.Clean dirt from around the spark plug. Remove the spark plug from the cylinder head by turning a 5/8 in. socket counterclockwise.

Feeler Gauge

Fig. 43

The recommended clearance for both intake and exhaust is

.003 – .006 in. (.076 – 0.152 mm). Use a standard automotive

.005 in. (0.127 mm) feeler gauge. The feeler gauge should slide between the rocker arm and valve stem with a slight amount of

3.Replace cracked, fouled or dirty spark plug. Set the air gap at 0.025 in. (0.655 mm.) using a feeler gauge (Fig. 45).

4.Install a correctly-gapped spark plug in the cylinder head. Turn the 5/8 in. socket clockwise until snug.

If using a torque wrench torque to:

110-120 in.•lb. (12.3-13.5 N•m)

Do not over tighten.

0.025 in.

(0.655 mm.)

Fig. 45

resistance, without binding. See Figures 43 and 44.

10.If the clearance is not within specification:

a. Turn the adjusting nut using a 5/16 inch (8 mm) wrench or nut driver (Fig. 44).

•To increase clearance, turn the adjusting nut counterclockwise.

WARNING: Do not sand blast, scrape or clean electrodes. Grit in the engine could damage the cylinder.

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