Please clear my one doubt that during idle condition, throttle valve suppose to be fully shut or we keep it little open? I think it has to be little open for taking air suck in and fuel through jet screw which will come after the throttle valve for mixing. Am I right sir?
Regarding your doubt. Yes we keep throttle valve completely closed during idling condition. Because during Idling condition the fuel is supplied using Idling jet (in video: Idling jet is numbered as 16)since this Idling jet is placed below Throttle, hence even when the throttle is not operated the engine gets the air-fuel mixture. Actually we have more than one jet in the carburettor. Main jet: This will come into working while the throttle is operated. Idle Jet: This comes in working when the throttle is not in use
There are different kinds of carburetors used in different bikes. Depending upon the type we have Idling settings incorporated. Sometimes this idling setting screw adjusts the slide(used for throttle) vertically such that by rotating the idle screw clockwise the slide (used for throttle) is raised and a wider passage is created for the passing of air fuel mixture hence more amount of air fuel mixture is supplied to the engine and it produces more power (High RPM) On the other hand turnjng thr idling screw anti-clockwise lowers the slide and decreases the passage area hence decreasing the supply of air fuel mixture thus reducing the power output produced by the engine.(i.e. decreasing the RPM)
i have a question here, could you explain the pilot jet holes ? how it works. you find some pilot jets have holes at the neck, wile others have holes down on the stem, what is the difference that will take place when the holes are up or down ?
The holes provided on the side of pilot jet are called as bleeding holes (The number of these vary with different manufacturers) These pilot jets (pilot jet with bleed holes) are used in those Carburettors where there is a air passage designed in the Carburettors in order to allow excess air coming in contact with pilot jets from the side and this air enters the pilot jet from the side then gets mixed properly with the fuel while flowing out throught it. Thus giving a better mixture.. Note: If you use pilot jet with bleed holes in place of piloy jet without bleed holes then basically you won't find any difference in operation since your Carburettor wasn't designed for the pilot jet with bleed holes and it is not having air passage for the same.
@@AllAboutMechanicalEngineering thank you for quick reply. you mean that this bleeding holes don't make big difference i can have if i change the pilot jet with more holes or less, but I read before that the numbers and its place on the stem are for high or low acceleration but i don't know this is right or wrong, beside, if i change a pilot jet with another one with more holes or less what kind of changes i will have ?
The pilot jets works during idling and progression ( i.e. during idling and low acceleration) so you are right there But at high acceleration the main jet comes into the picture and hence pilot jet is not so responsible for the high acceleration. If you are willing to replace the pilot jet, then as I said earlier, in case you are using pilot jet with bleeding hole in place of pilot jet without bleeding hole then there will not be any difference due to limitations of Carburettor design. Now if you are talking about replacing pilot jet with more number of holes (let us say using pilot jet with 4 holes instead of 2 holes) then if you are not altering the pilot air screw you may find slight change in performance. Since the mixture is of same kind as the air and fuel ratio has not been changed and slight improvement in performance will be due to more correct mixture preparation due to additional number of holes. But if you are altering the pilot air screw then the more you allow air to flow to the pilot jet the leaner mixture you will obtain and then rather of improvement of the performance you might have to face some issues such as backfire, sudden stopping, etc. So basically its not about the number of holes and there position, its about the design of the Carburettor and accordingly there is a suitable pilot jet which is to be used for that Carburettor. Use of wrong pilot jet is not going to give any improvement in performance
You can use IC.Engines by Mathur and Sharma. Or I. C. Engines by V. Ganeshan. There are other books as well. Try these, I hope it will be easier to understand the subject.
