mxu 50 Manuel atelier : Page 36

          1. GENERAL INFORMATION                                                                    ATV 50


 ENGINE LACKS POWER

 Inspection/Adjustment                      Symptom                  Probable Cause

 Start engine and
 accelerate lightly for
 observation.
                                                                     Clogged air cleaner
                             Engine speed        Engine speed does   Clogged fuel filter
                             increases           not increase        Clogged exhaust muffler
                                                 sufficiently        Faulty auto bystarter
                                                                     Faulty charcoal canister
 Check ignition timing
 (using a timing light).

                                                                     Faulty CDI unit
                             Correct timing      Incorrect timing    Faulty A.C. generator
 Test cylinder
 compression (using a
 compression gauge)
                                                                     Worn cylinder and piston
                              Normal                  Abnormal       rings
                              compression             compression    Blown cylinder head gasket
                                                                     Faulty reed valve
 Check carburetor for
 clogging


                              Not Clogged              Clogged       Clogged carburetor jets


 Remove spark plug and
 inspect


                           Plug not fouled or    Plug fouled or      Fouled spark plug
                           discolored            discolored          Incorrect heat range plug

 Check if engine
 overheats
                                                                     Mixture too lean
                                                                     Poor quality fuel
                             Engine does not     Engine overheats    Excessive carbon build-up in
                             overheats                               combustion chamber
                                                                     Ignition timing too early
 Rapidly accelerate or
 run at high speed
                                                                     Excessive carbon build-up in
                            Engine does not                          combustion chamber
                                                  Engine knocks      Poor quality fuel
                            knock
                                                                     Clutch slipping
                                                                     Mixture too lean




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