2. GENERAL INFORMATION VITALITY 50 POOR PERFORMANCE (ESPECIALLY AT IDLE AND LOW SPEEDS) Inspection/Adjustment Symptom Probable Cause Check ignition timing Faulty CDI unit Correct timing Incorrect timing Faulty pulser coil The woodruff key in the Check carburetor pilot crankshaft is not fixed position. screw adjustment Mixture too rich (turn screw Correctly adjusted Incorrectly adjusted out) Mixture too lean (turn screw in) Check carburetor gasket for air leaks Deteriorated O-ring Carburetor is not securely No air leak Air leaks tightened Damaged insulator rubber Broken vacuum tube Remove spark plug and install it into spark plug cap to test spark by connecting it to engine ground Faulty or fouled spark plug Faulty CDI unit Weak or inter- Faulty A.C. generator Good spark mittent spark Faulty ignition coil Broken or shorted spark plug wire Faulty ignition switch Check air cut-off valve Faulty air cut-off valve Good Faulty Damaged vacuum tube Clogged or damaged air vent hole 2-38