3. INSPECTION/ADJUSTMENT MXU 250R/300R SECONDARY AIR SUPPLY Vacuum Hose AICV Control solenoid Valve SYSTEM This model is equipped with a built-in secondary air supply system. The pulse secondary air supply system is located on the cylinder head cover. The secondary air supply system introduces filtered air into exhaust gases in the exhaust port. The secondary air is drawn into the exhaust port whenever there is negative pressure pulse in the exhaust system. This charged secondary air promotes burning of the unburned exhaust gases and changes a considerable amount of hydrocarbons and carbon monoxide into relatively harmless PAIR Check Valve Air Supply Hose carbon dioxide and water. Check the AICV (air injection control valve) hoses between the AICV control solenoid valve and cylinder head cover for deterioration, damage or loose connections. Make sure the hoses are not cracked. If the hoses show any signs of heat damage, inspect the AICV check valve in the AICV reed valve cover damage. Ignition Coil Cap Spark Plug SPARK PLUG Remove ignition coil cap and spark plug. Check the spark plug for wear and fouling deposits. Clean any fouling deposits with a spark plug cleaner or a wire brush. Specified Spark Plug: DPR7EA-9 3-7