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performance and cause the exhaust being      the inlet is relatively rough. When the mix-
                      not smooth. If the exhaust pipe is replaced   ture enters the inlet, there will be a certain
                      with a straight exhaust pipe, it can theoreti-  amount of gas attached to the inlet, and
                      cally increase the power by 15% .            when the inlet is smooth, the fuel efficiency
                                                                   can be improved. So as to improve per-
                      2. Change carburettor                        formance and reduce fuel consumption. It
                      There are several ways to change carbure-    takes a certain amount of patience to grind
                      tors in general:                             the inlet!
                      (1) change the carburetors with larger calib-
                      er.                                          5. Change ignition heating up curve
                             (2)Optimizing the main jet of the ex-  In general, there are ready-made unlimited
                      isting carburetor (properly enlarged) and the   speed igniters on the market that can be
                      main oil needle of the carburettor (re-grind-  used directly. It can increase the speed of
                      ing the fuel supply curve), finally adjusting   5 to 15 yards. If you’d like to run faster, you
                      the mixing ratio and enlarge air filter, so that   can make a new adjustment on the basis of
                      the engine can basically do so. The engine   changing the compression ratio. Generally,
                      can get at least 15 to 20 percent more pow-  after changing the compression ratio, the ig-
                      er, but it is not enough with these , and the   nition heating up curve can not adapt to the
                      transmission ratio has to be changed.        new compression ratio, and it will be easy
                                                                   to start the phenomenon of rebound and oil
                      3. Increase compression ratio                release, so the effect of high compression
                      There are many ways to increase the          ratio can be improved by improving the igni-
                      compression ratio: cylinder head welding,    tion heating up curve.
                      changing tip piston, changing ultra-thin cyl-
                      inder pad. Among them, changing ultra-thin   Things should be paid attention when refit-
                      cylinder pad is the safest way, but the ef-  ting.
                      fect is also the worst. It is more suitable for      1.More than 24mm diameter of the
                      fancier who do not have modification expe-   carburetor need to change the intake man-
                      rience to try.                               ifold, and 20mm or 22mm diameter do not
                                                                   need to replace the intake manifold.
                      4. Grinding inlet                                   2.Refitting carburettor is not the
                      As a result of the work of some small-dis-   bigger the better. A large carburetor, on the
                      placement motorcycle, the inner wall of      other hand, can cause excessive intake,

 10  JUNE    2019                                                     Motorcycle Reviews             china 2 wheels  11
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