MAINTENANCE AND REPAIR INSTRUCTIONS

If these statements are not true, repeat this step.

7.Slide the feeler gauge between the rocker arm and the valve return spring. Measure the clearance between the valve stem and rocker arm (Fig. 53). Measure both the intake and exhaust valves.

 

Adjusting Nuts

Rocker Arms

INTAKE

 

EXHAUST

Feeler Gauge

Spark Plug

Hole

Fig. 53

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 resistance, without binding. See Figures 53 and 54.

8.If the clearance is not within specification:

a.Turn the adjusting nut using a 5/16 inch (8 mm) wrench or nut driver (Fig. 53).

•To increase clearance, turn the adjusting nut counterclockwise.

•To decrease clearance, turn the adjusting nut clockwise.

b.Recheck both clearances, and adjust as necessary.

9.Reinstall the rocker arm cover using a new gasket. Torque the screw to 20–30 in•lb (2.2–3.4 N•m).

10.Check the spark plug and reinstall. See Replacing the Spark Plug.

11.Replace the spark plug wire.

12.Reinstall the engine cover. Check alignment of the cover before tightening the screws. Tighten screws.

Adjusting Nut

Rocker Arm

.003–.006 in.

(.076–.152 mm)

Feeler Gauge

Valve Stem

Fig. 54

REPLACING THE SPARK PLUG

Use a replacement part number 753-05255 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. Remove the six (6) screws on the back of the engine cover with a Flat-head or T-25 Torx screwdriver (Fig. 51).

2.Grasp the plug wire firmly and pull the cap from the spark plug.

3.Clean dirt from around the spark plug. Remove the spark

plug from the cylinder head by turning a 5/8 in. socket counterclockwise.

4.Replace cracked, fouled or

dirty spark plug. Set the air

0.025 in.

 

 

 

 

 

 

gap at 0.025 in. (0.655 mm.)

(0.655 mm.)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

using a feeler gauge (Fig. 55).

 

 

 

 

 

 

 

 

 

 

 

5. Install a correctly-gapped

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

spark plug in the cylinder

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

head. Turn the 5/8 in.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

socket clockwise until snug.

 

 

 

 

Fig. 55

 

 

 

 

 

 

 

 

 

 

 

 

 

 

If using a torque wrench torque to:

110-120 in.•lb. (12.3-13.5 N•m)

Do not over tighten.

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

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