Hey guys, so I'm going to create a video today on how to tune the carburetor. So I was under the impression that the video has already been covered. I did talk about it a bit in the cleaning video and in the video where you adjust the float. So it's good to clean the carburetor once every year at least because one, the quality of the troll is not that great in India as such and Kerala, the quality is pretty pathetic. Apart from that there is a good amount of rust in most of the bikes because the newest bike is at least 15 to 17 years old. So it is advisable that you clean the carburetor every now and then. So another important thing that I want to tell you is the carburetor is never tuned based on speed. It is always tuned based on throttle position. So there are three main throttle position or rather four that I will talk about. So right now the throttle is closed and this is how much is the full throttle. So you can see from here this you can look at this cut which is there from here till it moves around till here. So it's roughly around I would say 45 degree movement. So at the zero throttle position you have the pilot jets that provide fuel. If you go till about quarter throttle it is still the pilot jet. So till here if your bike is not functioning well it's not idling or if it is not running till quarter throttle that would mean it's the pilot circuit that you need to look at. So here from quarter throttle to about half throttle it is the pilot as well as the needle I mean the needle in the slide. So usually from the company the needle comes at a position which is second or third from the bottom. So usually see if you can put it there but in order to save mileage some people do play around with the needle position a bit. So that is still the three fourth throttle that is from zero to about half you have the needle running. So when you turn the throttle further from half to let's say full throttle that is when you have the main jet kicking in and at you know almost towards the last 20-25% it is the it's all jets functioning together. So you have to take a plug reading to understand if your bike let's say is bogging down or if it is producing too much of smoke and it is not moving forward that would mean that you know either your jetting is not on spot or there could be more oil in the fuel. So but both produces similar result so that's why I'm talking about. So I'll now talk about adjusting or tuning the carburetor you need a small flat slide carburetor. So there are two things that you can tune one is the air screw which is where I hope you guys can see which is where the screw driver is and then the idle screw. So in order for the engine to run you need an air to fuel ratio of about 15 is to 1. So that is 15 parts of air and one part of fuel. So when you're cold starting a bike that is the reason why you pull the choke because at that kind of a ratio cold bike cannot start so you will have to supply more fuel. Once it attains temperature then it can start at that ratio. So approximately that is what needs to be tuned in. So the air screw by default what you do is you tune it at around 1.5 turn out. So right now what I'm going to do is I'm going to make it fully tight. So that's how tight it can go and that is fully tight. You don't put a lot of pressure just gently and tight it. So now you open it 1.5 turns out. So that is half then that is one. Now it is one and a half. So that is your starting position and you just turn it a bit so that it starts easily otherwise it won't start. So let's start the bike. So you don't adjust the idle of the bike when the bike is cold. You always adjust it when it has reached temperature but I am not going to wait till then. So what I'm going to do is I'm going to slowly adjust it. So if you turn it anti-clockwise that would mean that you're bringing the slide down by taking the idle screw out. If you turn it clockwise that would mean that the slide is going up. You can hear there is an increase in the RPM. So what you should do is you should keep it a little more than minimum where the engine starts about to die. So if you look here the RPM is roughly around 1,200. So when the engine reaches operating temperature then it would idle little low but once it starts idling at that speed you slightly crank it. Then what you do is you look at the quarter speed. So while you are riding the bike if you feel that it is bogging down at a particular throttle position you have to always talk about throttle position not the speed. You cannot say you know my bike kind of dies at 80 kmph. That is not the right way of saying it. Always save it the throttle position. Now you can see the RPM has slightly risen that is primarily because the engine is slightly hot. So what you can do is right now you can reduce it even further. So I am just turning it a bit more off and you can see now it is idling almost perfectly at around 1200 RPM. So I will turn it off. So that is primarily how you tune the carburetor. So let's say there are a couple of troubleshooting steps that I will quickly tell you. If the bike doesn't start without choke at all. Like even if it is a warm bike and it is not starting right now. If I start this bike I am not pulling the choke. Let me just show you guys. It is starting. And let's say it doesn't start without a choke at all. It doesn't idle. That means your pilot circuit is blocked. So you need to clean the carburetor. Depending on which RPM range your carburetor or your bike is misfiring or in which throttle position it is misfiring or bogging down. You need to identify that and based on that you have to take a plug reading. So I will cover the plug reading in a different topic. But you need to see whether the mixture is lean or rich. If it is lean then you make it rich by making the jets slightly bigger if it is happening beyond half throttle. If it is happening till the half throttle position then first thing you do is you check if the pilot circuit is blocked. Clean the pilot circuit. Look at the position in which the needle is. So once you eliminate those two possibilities then what you need to do is you need to look at the main jet. So if let's say between half throttle and three fourth of the throttle if your bike is bogging down that would clearly mean that the main jet is causing problems. So you need to check whether it is lean or rich. If it is rich then what you need to do is you need to down jet. That means you have to put a jet which is of a smaller size. If it is lean then you have to object. So before objecting you have an option to check by removing the air filter. What happens is now you are letting more air in. So if you see the bike starts performing well things are fine between the throttle and full throttle. That would simply mean that the jet is actually bigger. So you need to bring it down. So that's it for today. I hope you learned something from the video. Thanks a lot for watching. Please like, share and subscribe. Thank you.