Troy-Bilt TB625 Operation Manual - Page 16

ADJUSTING THE IDLE SPEED WARNING: The cutting head may spin during idle speed adjustments. Wear protective clothing and observe all safety instructions to prevent serious personal injury. NOTE: Careless adjustments can seriously damage the unit. An authorized service dealer should make carburetor adjustments. If, after checking the fuel and cleaning the air filter, the engine still will not idle, adjust the idle speed screw as follows: 1. Start the engine. Refer to Starting and Stopping. 2. Release the throttle control and let the engine idle. If the engine stops, use a small Phillips screwdriver to turn the idle speed screw clockwise, 1/8 of a turn at a time (as needed) until the engine idles smoothly (Fig. 25). 3. If the engine is idling too quickly, turn the idle speed screw counterclockwise, 1/8 of a turn at a time (as needed) to reduce the idle speed (Fig. 25). Checking the fuel, cleaning the air filter, and adjusting the idle speed should solve most engine problems. If not, and any of the following conditions are true, take the unit to a qualified service dealer: • the engine will not idle • the engine hesitates or stalls on acceleration • there is a loss of engine power MAINTAINING THE SPARK PLUG 1. Stop the engine and allow it to cool. Grasp the spark plug boot firmly and pull it from the spark plug. 2. Clean around the spark plug. Remove the spark plug from the cylinder head with a 5/8-inch socket, turning counterclockwise. WARNING: Do not sand blast, scrape or clean spark plug electrodes. Grit in the engine could damage the cylinder. 3. Inspect the spark plug. If the spark plug is cracked, fouled or dirty, replace it with replacement part #753-05784, a Champion RDZ4H or an equivalent spark plug. 4. Use a feeler gauge to set the air gap at 0.025 in. (0.635 mm) (Fig. 26). 5. Install the spark plug in the cylinder head. Tighten the spark plug with a 5/8-inch socket, turning it clockwise until snug. NOTE: If using a torque wrench, torque to: 110-120 in.•lb. (12.3-13.5 N•m). Do not over tighten. 6. Reattach the spark plug boot. Idle Speed Screw Fig. 25 0.025 in. (0.635 mm) Fig. 26 16