Craftsman 79194 Operation Manual - Page 12

ROCKER ARM CLEARANCE This requires disassembly of the engine. If you feel unsure or unqualified to perform this, take the unit to a Sears or other qualified service dealer NOTE: Inspect the valve to rocker arm clearance with a feeler gauge after the first 10 hours of operation and every 25 hours of operation. • The engine must be cold when checking or adjusting the valve clearance, • This task should be performed inside, in a clean, dust free area. 1. Remove the six (6) screws on the back of the engine cover with a Flat-head or T-25 Torx screwdriver (Fig. 30). View Of The Rear Engine Cover [ [ [ Remove Screws Remove Screws • Both rocker arms move freely, and both valves are closed. If these statements are not true, repeat step 6. 7. Slide the feeler gauge between the rocker arm and the top of each valve stem. Measure the clearance between the valve stem and rocker arm (Fig. 33). Measure both the intake and exhaust valves. Adjusting Nut _ Rocker Arm .003-.006 in. (.076-.152 mm) FeelerlGauge Fig. 30 2. Disconnect the spark plug wire. 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. Remove the engine cover (Fig. 30). 5. 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. 31). Remove the rocker arm cover and gasket. 6. 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. Look in the spark plug hole to view the piston (Fig. 32). Rocker Arms INTAKE Rocker Arm Cover Fig. 31 Nuts EXHAUST Feeler Gauge Spark Plug Hole Fig. 32 Fig. 33 Valve Stem 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 32 and 33. 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. 33). • 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 Nom). 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. REPLACING THE SPARK PLUG WecyleAlicnRtdrNoedIrN.eGs.: GrDitoinnothtesaenndginbelascto, usldcradpaemaogreclethaen Use a replacement part number 753-05255 or Champion spark plug, #RDZ19H. The correct air gap is 0.025 in. (0.635 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. 30). 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. Replace cracked, fouled or dirty spark plug. Set the air gap at 0.025 in. (0.635 mm} using a feeler gauge (Fig. 34). (0.635 mm) 0.025 in. _r + Fig. 34 12