Learn How to Tune Bike Carburetor for Mileage


Do you have to increase the throttle each time so as to get your engine started? Does the engine tend to overheat even when you haven’t raced it that much? Or, has your bike lost that smooth acceleration that it had earlier? All such situations might be possible and they aren’t the favorable ones. Nobody wants their bike to perform poorly. So, what can you do in such situations? Well, tuning your bike might be the best possible option so as to improve the efficiency and performance. Setting and tuning to push the correct mixture of fuel and air would help in extending your bike's engine life. This tuning is done with the carburetor and most people often wonder as to how to tune it?

Well, the great thing is adjusting this carburetor is quite easy and doesn’t require any special tools. This guide aims at helping you to tune your bike so that it can deliver its best.

Table of Content

Carburetors: How they Work and Basic components of a Carburetor

Anatomy of a Float Chamber

Understanding the Basics of Tuning Your Bike Carburetor

How to Tune Bike Carburetor for Mileage

How to Increase Bike Mileage

Summing Up

Carburetor: How it Works

To answer the question as to how to tune bike carburetor for mileage, you first need to understand everything about the carburetor. The carburetors supply fuel to the engine with the help of a phenomenon which is referred to as Vacuum Venturi Effect. Air makes its way into the carburetor through the air intake and then speeds up drastically because of the narrow interior walls of the carburetor.

The air blows perpendicular into the throttle slide which is basically a valve that is controlled by the throttle cable. As soon as the throttle is opened, the throttle slide is raised with the help of the cable.

As this slide begins to rise, the air pulls the fuel up the main jet through the float chamber. The fuel then gets mixed with the air and makes its way to the engine. The amount of fuel that flows in is completely dependent on the size and position of the needle, fuel level’s height and the size of the main jet.

More air is forced through the venturi tube in the carburetor when more throttle is applied to the vehicle. This helps in drawing more fuel into the engine.

As the vehicle ages over the years, it may develop vacuum air leaks from the various vacuum lines that are present in the engine compartment. These leaks present in the tube can lead to additional air being drawn into the intake manifold. This changes the volume of air or fuel mixture from the perfect blend to a more lean mixture. This, however, is a very common issue and can be resolved quite easily with carburetor tuning.

Photo of Learn How to Tune Bike Carburetor for Mileage 1/2 by Sanjay Mulje
How a Carburetor Works

Anatomy of Float Chamber

Now that you know how a carburetor works and its basic components, it’s time to know about float chamber and its parts.

The float chamber is basically a reservoir for the fuel and generally, contains all of the working components of the float. You would notice that in most modern bikes, the float chambers are attached to the carburetor base. Also, a drain would also be fitted to measure the length of the fuel or in general for maintenance purposes.

If you look really carefully into the float chamber, you would be able to find the float. This is the device that is responsible for controlling the amount of fuel that would enter the float chamber.

Components of Float Chamber


Needle valve assembly

Float pivot Rod

Drain Plug

Chamber and Gasket

The Float and Needle

As discussed above, the bike carburetor has floats. Now, these are made up of either plastic or brass. The float chamber works like a toilet tank and the floats basically float in the fuel. When the fuel is drawn up to the jet, the level of fuel present in the chamber basically drops. Henceforth, the float drops too.

When this happens, the needle valve would open up and this would give way to more fuel. Now, when the float rises with the fuel level, the needle valve would close the supply of the fuel.

Photo of Learn How to Tune Bike Carburetor for Mileage 2/2 by Sanjay Mulje
Inside Float Chamber

Symptoms of Incorrect Float Heights

There might be cases wherein if the floats are set too high. If this happens the fuel would overflow via the drillings present inside the body of the carb. The fuel might even flow into the engine. In case the engine is in a stationary mode, it can lead to hydraulic lock.

However, fuel leaking from the carb isn’t a good sign and can lead to a serious issue like fire if left unresolved. If the bike is running and the height of the fuel level is way too high, the engine would display a rich running condition.

This, in turn, would make the response of the throttle rather slow and the engine note muffled. If this ever happens, you would notice a very strong and unburnt smell of the fuel coming from the muffler.

However, if the fuel is way too low, the engine would start showing a lean running condition wherein the engine typically would hesitate before starting.

Understanding the Basics of Tuning Your Bike Carburetor

If you find that your engine is running too rough, it might be time to look into the matter and take corrective measures. Before we begin, it is essential that you know the fundamentals.

As its quite obvious, each bike has an engine and a carburetor. This carburetor is basically the heart of your bike. In this guide, we are going to assume that your engine isn’t damaged and isn’t dead.

Now, you must definitely be aware as to where your bike carburetor is. To get started, what you need is a basic screwdriver in hand. Also, before you do this, your bike must have finished a minimum of one service –500 kilometers or more on the odometer.

To correctly notice the improvements after tuning remember to not change the fuel type that is Speed, Power, Normal Unleaded, Extra Premium etc. Run the bike on the same fuel type so you can assess the improvements made by tuning correctly. Now let's get going to how to actually do the tuning.

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