45
0.030 inch
(0.76 mm)
12
13 15
15
13
14
16
12. Unplug electrical wires (12) on back of ignition switch (13).
13. Pull tube (14) off the back of the primer bulb (15).
14. Lift rear upper cover and lay it to the side of the unit.
IMPORTANT:
The recoil rope will still be attached to the upper
cover.
IMPORTANT:
Inspect the fuel tank, fuel lines, primer bulb, spark
plug wire, and electrical wires for cracks or damage.
15. Disconnect the spark plug (16) wire from the spark plug.
16. Clean around the spark plug.
17. Remove the spark plug from the cylinder head.
IMPORTANT:
Replace a cracked, fouled, or dirty spark plug. Do
not clean the electrodes because grit entering the cylinder can
damage the engine.
18. Set the gap on the plug to 0.030 inch (0.76 mm).
19. Install the spark plug and torque it to 20–22 ft-lb
(27–30 N-m).
20. Connect the spark plug wire (16) to the spark plug .
21. Reattach primer bulb tube (14) to primer bulb (15) and elec-
trical wires (12) on back ignition switch (13) of rear upper
cover.
22. Set rear upper cover (11) in place so the two screw holes
line up with the rear lower cover and side covers .
23. Reattach two screws (10) through the rear covers and into
the clip on the side cover.
24. Remove top oil fill cap (6).
25. Set top cover (8) in place and snap three top cover clips (9)
into the rear upper cover (11).
26. Reinstall top oil fill cap (6).
27. Reinstall two screws (10) in the side covers that attach to
the clips on the top cover.
28. Reinstall two screws (4) in the plenum (5) that attach to the
top cover (7).
29. Reinstall discharge chute (1) with the hardware removed in
step 5.
Summary of Contents for ST 121E
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