Electrical System SPARK PLUGS Normal Spark Plug Component and Details Plug taken from an engine operating under normal conditions will have light tan or gray colored deposits. If center electrode is not worn, plug can be set to proper gap and reused. Worn On a worn plug, center electrode will be rounded and gap will be greater than specifi ed gap. Replace a worn spark plug immediately. Wet Fouled NOTE: Do not clean spark plug in a machine using abrasive grit. Some grit could remain in spark plug and enter engine causing extensive wear and damage. Engine misfi re or starting problems are often caused by a spark plug that has improper gap or is in poor condition.
Engine is equipped with following spark plugs: Refer to Maintenance for Repairs/Service Parts. A wet plug is caused by excess fuel or oil in combustion chamber. Excess fuel could be caused by a restricted air cleaner, a carburetor problem, or operating engine with too much choke. Oil in combustion chamber is usually caused by a restricted air cleaner, a breather problem, worn piston rings, or valve guides. Service Clean out spark plug recess. Remove plug and replace. 1. Check gap using wire feeler gauge. Adjust gap to 0.76 mm (0.03 in.). 2. Install plug into cylinder head. 3. Torque plug to 27 N·m (20 ft. lb.). Inspection Inspect each spark plug as it is removed from cylinder head.
Deposits on tip are an indication of general condition of piston rings, valves, and carburetor. Normal and fouled plugs are shown in following photos: 28 KohlerEngines.com 66 690 01 Rev. C CAUTION Electrical Shock can cause injury. Do not touch wires while engine is running. A B C D A Wire Gauge B Spark Plug C Ground Electrode D Gap Gap 0.76 mm (0.03 in.) Thread Size 14 mm Reach 19.1 mm (3/4 in.) Hex Size 15.9 mm (5/8 in.)