Why Do Motorcycles Have A Reserve Tank? (Explained!)

Why Do Motorcycles Have A Reserve Tank? (Explained!)

Fuel reserve, or reserve as many individuals call it – is the crisis fuel which a motorcycle has when you are low on fuel.

The reserve fuel will normally comprise of 1–1.5 litres in the fuel tank.

So, why do motorcycles have a reserve tank? A reserve tank is a part of the main fuel tank designed as a fallback option for the rider in case the fuel runs out in the main fuel tank. The motorcycle rider can then switch to reserve and use this reserve fuel to travel to the nearest gas station.

Let’s dive right into the specifics and the uses of reserve tank in a motorcycle.

Why Are There Reserves In Motorcycles?

Motorcycle reserve is planned as a fail safe choice in case the fuel runs out in the main tank.

The motorcycle rider can switch from main tank to reserve tank to use the reserve fuel to reach the nearest gas station.

The reserve fuel will assist the rider with traveling a couple more miles and reach the nearest gas station to top off the tank.

And that’s exactly why you have reserve in your bike. It helps to have some extra fuel in case we run out of gas in our motorcycle. We can use the reserve to travel to the gas station and refill the tank.

How Does Reserve Work In A Motorcycle?

Firstly, reserve tank is not a separate tank but rather a apart of the main fuel tank in your motorcycle.

The fuel valve (petcock valve), when in ON position and not on RES, will block the the fuel in reserve to flow to the carburetor and then to the engine.

A diagrammatic representation is given below. As you can see, the reserve fuel switch or the fuel valve is blocking the flow of the reserve fuel.

So, whenever you turn the reserve fuel switch to RES position, the blockage will be removed and the reserve fuel will then be free to flow into the carburetor and then to the engine to keep the motorcycle running.

Simply put, reserve tank is a part of the main tank where the fuel valve puts a barricade for the reserve fuel to flow into the carburetor.

Once you switch to the reserve tank in reserve fuel switch, you are essentially removing the barricade and allowing the reserve fuel to flow into the engine so that your motorcycle keeps running.

When Should I Put My Bike On Reserve?

There two occasions when you should put your bike on reserve.

  1. when you run out of fuel in the main tank
  2. when you have not used reserve in a long time

It is obvious for you to use the reserve when you run out of gas in your main fuel tank. You are stuck with no fuel and reserve is your savior to use the fuel and get to the nearest gas station as early as possible.

Make sure that you use the reserve tank for exactly what it is built for – a reserve to be used to go to the nearest gas station and refill the main tank. Do not overstretch and end up with your reserve fuel tank emptied out as well.

Another reason why you should switch to reserve is when you have not used it in a long time.

Usually, I switch to reserve once in every 3 months if I have not used the reserve in that period.

This is to ensure that the fuel on the reserve tank gets emptied out and does not get accumulated with dirt overtime. Leaving the fuel for longer periods of tie can result in the fuel clogging the fuel lines and carburetor.

So make sure to switch to reserve once in 3 months if you haven’t used the reserve fuel for a long time.

How Much Fuel Is In The Reserve Tank?

Roughly around 10% to 15% of the total fuel tank capacity will be in the reserve tank.

When we say fuel tank capacity, it includes both the main tank and the reserve tank capcaities.

For example, in a motorcycle with fuel tank capacity of, say, 8 litres – around 7 litres of fuel would be in the main tank and the rest 1 litre will be in the reserve tank. This 1 litre can be used once you run out of fuel in the main tank.Related Questions

Can I Run My Motorcycle On Reserve All The Time?

It is not recommended to run your motorcycle on reserve all the time.

If you are keeping the Reserve fuel valve ON all the time, you will not have a safety fuel to fall back on when the fuel is emptied out. Here, both the reserve and the main tank fuel will be emptied out if you are on reserve all the time.

In addition, you won’t get to know when the main fuel tank was emptied earlier. You can guess the low gasoline levels from the fuel gauge, and that would be your cue to visit the gas station immediately.

On the other hand, you should occasionally run your motorcycle on reserve. Running on reserve now and again will allow you to utilize fuel that is in the lower part of the fuel tank.

Here is a detailed post discussing on the pros and cons of running on reserve all the time.

How Should I Put My Motorcycle On Reserve?

To put your bike on reserve, you need to turn reserve fuel switch (fuel valve) from ON position to RES position.

The reserve fuel switch has three positions namely – ON, OFF, RES.

OFF position is to stop the flow of fuel to the engine and ON is the exact opposite of that – to continue the fuel running from tank to the engine.

RES position is when the fuel flow switches from the main tank to the reserve tank to flow to the engine (carburetor to be precise, but eventually to the engine).

So, to put your motorcycle on reserve, all you need to do is turn the fuel valve to RES position.