Troy-Bilt 182826 TB4000 - Manual (Page 23)

23
Maintenance (continued)
9. If the clearance is not within specification:
a. Turn the adjusting nut using a 5/16 inch (8 mm)
wrench or nut driver (Fig. 6-19).
To increase clearance, turn the adjusting nut
counterclockwise.
To decrease clearance, turn the adjusting nut
clockwise.
b. Recheck both clearances, and adjust as neces-
sary. Clearance for both intake and exhaust is
.003–.006 inch (.076–.0152 mm)
10. Reinstall the rocker arm cover using a new gasket.
Torque the screw to 20–30 in•lb (2.2–3.4 N•m).
Remove
Screws
Back of Engine
Loosen
Screws
Remove Screw
Engine Cover
Rocker Arm Cover
Adjusting Nut
Feeler
Gauge
Rocker Arm
Gasket
Spark Plug
Hole
11. Reinstall the engine cover. Check alignment of the
cover before tightening the screws. Tighten screws.
12. Check the spark plug and reinstall. See Replacing
the Spark Plug.
13. Replace the spark plug wire.
REPLACING THE SPARK PLUG
Use a Champion RDZ19H spark plug (or equivalent).
The correct air gap is 0.025 inch (0.655 mm). Remove
the plug after every 50 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
inch socket counterclockwise.
3. Replace cracked, fouled or dirty spark plug. Set the
air gap at 0.025 inch (0.655 mm) using a feeler
gauge (Fig. 6-20).
Do not sand blast, scrape, or clean electrodes.
Grit in the engine could damage the cylinder.
4. Install a correctly gaped spark plug in the cylinder
head. Tighten by turning the 5/8 inch socket clock-
wise 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 inch
(0.655 mm)
Fig. 6-19
Fig. 6-20
Fig. 6-18
Fig. 6-17
Fig. 6-16