Inlet And Exhaust System; The Structure And Working Principle Of Air Cleaner; The Structure And Working Principle Of Inlet Pipe; The Structure And Working Principle Of Exhaust System - ZONGSHEN ZS250GY-3 Service Manual

The inlet system of engine mainly consists of air cleaner and inlet pipe.The main function of which is
to guide and filtrate air,reduce inlet noise and control the volume of mixed gas which is going to engine.
The exhaust system mainly consists of exhaust pipe and muffler.The main function of which is to
transfer the exhaust gas to atmosphere,reduce the noise when exhausting and the temperature of exhaust
gas and eliminate the spark in exhaust gas.A good exhaust system can advance the inlet and exhaust
system,increase engine power and reduce the fuel consumption,so it is also called exhaust muffler.
1 The Structure of Inlet System

[1]The Structure and Working Principle of Air Cleaner

Air cleaner is the important component of inlet system.The function of which is to filtrate,purify
the air entering into cylinder,avoid dust,sand entering into cylinder so that it will reduce the abrasion of
cylinder,piston and piston ring.Its performance has a big effect on the motivity of engine,noise of inlet and
service lifetime.Experiences indicate the abrasion of cylinder will increase 8 times ,the abrasion of piston
will increase 3 times and the abrasion of piston ring will increase 9 times if air cleaner is not installed.In
this way,the reliability of engine will reduce and the service lifetime will be shortened.Therefore,motorcycle
must be installed with air cleaner. The requirement of air cleaner is not only to filtrate the air,but also the
resistance of air flowing must be small so that the volume of engine inlet will enhance.More requirements
are reliable working performance,simple structure,small dimension of appearance,light body and easy to
maintain.The air cleaner mainly consists of element and sealed box.When engine runs,air will enter into
the front cavity of air cleaner through air pipe,then flow into the rear cavity after filtration.and finally enter
the throttle.

[2]The Structure and Working Principle of Inlet Pipe

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Section 3

Inlet and Exhaust System

Inlet pipe is the important component to
connect throttle and engine inlet.Meanwhile,it
has a function of supporting throttle and has a
simple structure.Its bending shape depends on the
position which the throttle should be corresponding
to the engine inlet,but you should think about the
influence of inlet resistance.If the pipe is long,it has
an advantage of fuel pulverization,but air resistance
is big.If the pipe is short,which is not good for fuel
pulverization,but air resistance is small.
The mixed gas after pulverization of throttle
flows into cylinder through inlet pipe and engine
inlet.The inlet pipe reduces the heat which engine
has transferred to throttle and separates the shake
of engine from throttle.
2 The Structure and Working Principle of Exhaust
System
The exhaust pipe in exhaust muffler is made
of bending steel pipe.It locates between exhaust
vent of engine and muffler.Its funtion is to guide
the exhaust gas from engine to the muffler.