Carburetor

The most interesting part that i found out in bike was the carburetor,although it is very easy to understand,its simplicity and effectiveness should not be ignored.
A carburetor system has the following important parts:-
1)Float chamber
2)Float
3)Main body
4)Main metering jet
5)Secondary metering jet
6)Throttle system
7)choke
8)Idling screw

Basic function of the carburetor is to produce a combustible mixture of fuel and air and supply it to the engine.

We will discuss these in somewhat detail now
1)FLOAT CHAMBER:-
        Float chamber is the part which you see situated at the bottom of your carburetor.(Sorry forgot to capture it.)It a small simple vessel which contains fuel.And it was the only part inspected during servicing of the vehicle by mechanic(Don't know about others but according to him,uninstalling it completely and cleaning is not worth it).Most of the impurities are present inside float chamber such as water.A small opening is given to it so that it remains open to atmosphere and its easy to withdraw petrol inside it.A rubber pipe is connected to the opening so as to ensure petrol does not get exposed on engine parts however it is drained to the surface.

2)FLOAT:-
       

As you can see in the image the bottom pink part is float-a small plastic which floats and restrains the flow of petrol from main tank to float chamber.Whenever the petrol in float chamber attains a certain level the float restricts its flow into the float chamber.Float is pivoted to main body,if that pivot is displaced from its position then fuel continues to flow into float chamber and drains to the bottom surface via rubber pipe.
3)Main body:-
        Main body is the overall part on which various parts are mounted such as float chamber,float,choke,main metering jet,secondary jet,throttle system,idling screw.As far as I can think of its basically divided into four parts:-
        i)Air inlet:-
                Air inlet is given through a fibre pipe via air filter.This inlet is situated to right hand side if you look at carburetor on bike from left of the bike(do i sound confusing?).Space is provided for choke installation.
        ii)Fuel inlet:-
                Fuel enters from main and secondary metering jets at the center of carburettor.
        iii)Throttle system:-
                Space is provided at the top of main body to accommodate throttle system consisting of spring and needle.
        iv)Mixture outlet:-
                This is the part where a mixture of air and fuel is provided to the inlet manifold depending upon the whether bike is on cruising/accelerating/idling mode.
4)Main metering jet:-
        This is situated right below throttle system.The needle connected to throttle wire rests inside it.It is same as what we learnt in Solex carburetor.This metering jet has holes 4 set of paired holes.As we operate throttle the more and more holes get open and hence more fuel is provided to engine.The lower part of it is obviously dipped in petrol in Float chamber.

5)Secondary metering jet:-
        I really want your help in this.I was unable to get this information from the mechanic.Sorry about that.But I have got few pics.

6)Throttle system:-
        It consists of throttle wire and spring arrangement.The springs tends to expose less and less holes of metering jet.

7)Choke:-
        This is basically provide rich mixture of fuel and air during cold staring by restricting the flow of air into carburettor.

8)Idling screw:-
        Idling screw adjustment is very much important considering our bike is most of the time in idling mode while in city.The behaviour is quiet opposite of what we learnt.I thought that tightening it would reduce the supply of fuel but I was wrong as such act increases the amount of fuel going to engine.



Working:-
        When you turn your fuel lock from OFF to On or Reserve petrol flows from fuel filter to the float chamber.Whenever fuel reaches a certain level float restricts more supply of it.Now suppose you engine is cranked by kick or starter motor.The suction stroke of the engine causes air to be sucked from carburetor.Now while the air flows from air filter to the inlet manifold via carburetor,the venturi shape of the carburetor main body causes pressure drop at the tip of metering jet.This low pressure is sufficient to draw petrol from float chamber to the central part of carburetor through metering jet.Idling screw port also comes into play while starting condition(if choke is operated),while it is out of use during cruising or accelerating mode.This combustible mixture of fuel and air is provided to engine.(I am not going to write much about it as you will find its information anywhere on Internet.)


Now we will see if you are facing some problems of your bike and you are concerned that it has got something to do with the carburetor just go for the following steps:-
1)If you are facing the problem that your bike engine shuts down when you are on neutral and didn't race the throttle.The reason may be a problem in iding screw.In that case you can just slightly tighten the screw(a 1/4 of turn is sufficient) and then try keeping bike in neutral,I think your problem may get solved.

Try again and you might get lucky.
3)Other problems might arise due to blockage of metering jet holes or pores.This problem seldom arises and I have not experienced such thing happening,but in this case you have to completely remove carburetor and look for metering jet to clean them.

One thing I though would increase average of my bike is the loosening the idling screw and restraining fuel to be used more during idling.But my theory was wrong according to the mechanic and I somewhat agreed to him after hearing the explanation.The point is when you limit fuel during idling its going to cost you more while you accelerate from standing position to moving condition.More fuel is used for acceleration as compared to that during idling.So your idling screw must be at optimum position so that neither it causes to consume more fuel during idling nor during acceleration.

Another thing the mechanic warned me about not giving choke even in starting trouble conditions.He said to operate it only when you are running low on petrol.Don't know why he said that,can you guess????
(If you go for repairing your own bike for such small problem after reading this,I am not to be held responsible for any malfunctioning that might cause to your bike,these are thoughts of a noob.Mark my words go the the mechanic and get the problem solved.Once you have seen the process they use to tackle the problem you can give yourself a try.)

My first post

My first Post and some of the following are all about my experiences of work in local Servicing and repairing workshop of Hero Honda bikes.


I will be writing about random things and today I am going to write about 'Clutch'.

Before I go into the questions,I want you to know some of the basics of clutch assembly that I understood.

Clutch assembly is placed on the right hand portion of your bike the place covered near the rear wheel brake paddle.

It has following parts:-
1)GPD gear(i really don't know the significance,if you know please be free to share it)
2)Clutch housing
3)INNER
4)Clutch plates-4 in nos
5)Pressure plates-3 in nos
6)OUTER
7)Assembly of clutch wire to operate a small part which separates or interlock the clutch and pressure plates.

Working:-
The Gpd gear is directly mounted on the crank shaft.It is comparatively small(I forgot to measure the number of teethes)
The GPD gear drives a larger gear which is permanently fastened to the clutch housing.
The clutch housing is free to rotate and it is not connected to the gear box.
The part called INNER has 4 extrusions which are tapped holes to accommodate bolts.
Clutch plates and pressure plates are placed alternately and are in between the parts INNER and OUTER.
The part known as 'OUTER' has 4 holes,these holes co inside with that of INNER and accommodates the bolts-spring assembly.
Outer is connected to the gearbox.
When you press clutch,the small cam in clutch wire assembly operates and causes the springs around bolts to compress,this in turn results in increase in distance between the INNER and OUTER.So the clutch plates and pressure plates disengage to cause GPD->Clutch housing->INNER to rotate while OUTER remains stationary(or at the speed of wheels)due to the load applied to it via gearbox.
Now you change the gear and engage clutch slowly to result smoother transmission of power from rotating INNER -> clutch and pressure plates ->OUTER ->gearbox->rear Wheel.
(I know it sound somewhat strange but you will definitely get it if you see that assembly actually.)

 Clutch plate

Pressure plate

I had few questions about clutch,such as whether it is useful to press the clutch while you are riding on a slope.The answer I got is:-

1)NO do not press clutch while you are driving on slope as it is the obvious cause of slipping of vehicle while you brake.
2)This type of clutch usage also contributes to wearing of clutch plates and INNER,OUTER parts of clutch assembly.As mentioned above the INNER rotates and hence rubs with the clutch plate contiguous to it,causing wear of that plate as well as INNER.Also as OUTER is moving due to rotation of wheel,thus the one in contact with OUTER also wear out.

    Hence you should clutch only when you want to change the gear not otherwise.You may think such type of clutch usage while on slope may increase average of your bike but the effect is not so significant.However it causes harm to essential elements of clutch assembly.

(All the information is solely drawn from my experiences,so I might be wrong,please feel free to write,i really appreciate your views and comments.)