mxu 250 300 Workshop-manual : Page 31

          1. GENERAL INFORMATION                                                                    MXU 300/250


 POOR PERFORMANCE (ESPECIALLY AT IDLE AND LOW SPEEDS)



 Inspection/Adjustment                          Symptom                      Probable Cause


 Check ignition timing



                                                                           Faulty ignition unit
                               Correct timing        Incorrect timing
                                                                           Faulty pulser coil

 Check carburetor air
 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 not securely
                                 No air leak              Air leaks        tightened
                                                                           Damaged insulator rubber

 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 ignition unit
                                                      Weak or inter-       Faulty A.C. generator
                                 Good spark           mittent spark        Faulty ignition coil
                                                                           Broken or shorted spark plug
                                                                           wire
                                                                           Faulty ignition switch




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