Check When Idling Poorly or Power Is Insufficient

1. Check whether the choke is fully opened after the engine starts.

2. After stopping the engine, remove the spark plug and check it for carbon deposits and sparking condition.

3. Check whether the carburetor leaks, whether the float is stuck, and whether the needle valve is stuck.

4. Check whether the valve clearance is appropriate (adjust it when the engine is cold; the intake valve clearance is 0.1–0.15 mm and the exhaust valve clearance is 0.15–0.2 mm. Method: remove the starter cover assembly and the cylinder head cover, rotate the flywheel; when the scribe line on the flywheel outer edge is at the bottom, rotate the flywheel clockwise and counterclockwise. If both the intake and exhaust valves remain still, it indicates the piston is at top dead center of the compression and power strokes, and the valve clearance can now be adjusted. If the scribe line on the flywheel outer edge is at the bottom and, when rotating the flywheel clockwise and counterclockwise, the valves are moving, it indicates the piston is at top dead center of the exhaust and intake strokes, so rotate the flywheel one more full turn before adjusting.)

5. Adjustment method for the valve clearance adjusting nut: loosen the small nut on the rocker arm, adjust the ball nut beneath it, use a feeler gauge to control the valve clearance, then hold the ball nut with a wrench and tighten the small nut on the rocker arm with another wrench. After adjustment, use the feeler gauge to recheck whether the clearance is within the standard range; if not, readjust by the above method until it meets the standard.

6. Adjust the governor arm (for 173/177/182/188: loosen the governor arm connecting bolt, push the governor arm toward the cylinder head to its maximum position, turn the vertical shaft clockwise until it cannot turn further, keep the governor arm and the vertical shaft fixed, and tighten the connecting bolt. For 168/650/950: loosen the governor arm connecting bolt, rotate the governor arm in the direction of maximum throttle opening, turn the vertical shaft in the direction of maximum throttle opening, keep the governor arm and the vertical shaft fixed, and tighten the connecting bolt.)

7. Rotate the adjusting screw to adjust the tension of the governor spring; tightening it increases the engine speed and increases power.

8. Clean the air filter foam or remove the dust from the air filter element.

9. For two-stroke engines, remove the cylinder head and cylinder block and remove the carbon deposits on the cylinder head, cylinder block, spark plug, and piston.

10. Check whether the carburetor is blocked; if necessary, replace the carburetor and test.