Execution order
1. After removing the spark plugs, inspect them.
2. If the insulator of the central electrode of the spark plug is covered with a light brown or gray-steel color carbon deposit, then the carburetor is adjusted correctly and the spark plug is working normally.
3. Light gray or white color of the insulator contamination indicates that the mixture is very lean, black carbon on the spark plug indicates that the mixture is too rich.
4. If the spark plug electrodes and insulator are oily, this means that either the spark plug is sparking intermittently or the piston rings are worn out.
5. Before installation, the spark plugs must be cleaned with a wire brush, washed with gasoline and dried.
6. Adjust the gap between the spark plug electrodes by bending the side electrode. The central electrode must not be bent. Tighten the spark plugs to a torque of 20 N·m (2.0 kgf·m).