Can You Run A Motorcycle on Reserve All the Time?

Are you worried about what may happen if you are running your motorcycle on reserve all the time? Well, you are not the only one. Many riders will be wondering how the reserve on their motorcycle actually works and when they should use it.

Can I run my motorcycle on reserve all the time? You can run a motorcycle on reserve all the time. Running your motorcycle on reserve is not bad for the motorcycle. In fact, it is recommended to run your motorcycle on reserve occasionally. However, if you run your motorcycle on reserve when you run out of fuel, you are really out of fuel.

In the article below, I go into more detail about everything you need to know about the reserve, how you should use it, and the pros and cons of doing so.

A close up of a motorcycle's fuel tank.

How does the reserve on a motorcycle work?

I’ve heard several different misconceptions about how the reserve tank on a motorcycle works. The fact that it is called a reserve tank can cause people to draw a few wrong conclusions.

The reserve tank is part of the motorcycle’s main gas tank.; it is not separated in any way, shape, or form from the main tank.

How to switch to the reserve on a motorcycle?

The fuel petcock is how you switch between the reserve and the main fuel tank. The fuel petcock is located below the fuel tank will usually have three different positions.

  • “ON” – This is the normal position in which the fuel petcock should be left. While in the “ON” position, the fuel will flow normally from the tank to the carburetor when the engine is running or being started.
  • “OFF” – The “OFF” position will prevent any fuel from flowing to the carburetor.
  • “RES” – The “RES” position allows fuel to flow normally from the fuel tank to the carburetor when the engine is running or being started while using the reserve fuel supply in the fuel tank.

That being said, some fuel petcocks will also have another position that can be selected.

  • “PRI” – The “PRI” position on the petcock stands for prime. This position is used only when you need to fill up the carburetor after long-term storage or running out of fuel. The “PRI” position will allow fuel to flow into the carburetor even if the engine is not running. Once the engine is running, the fuel petcock should be returned to the “ON” or “RES” positions.

How does the reserve on a motorcycle work?

Now that you know how to switch between the main and reserve tank, you may be wondering what exactly is the difference between the two.

In layman’s terms, the fuel petcock has two metal tubes that go into the fuel tank and through which the fuel will flow from the tank and into the carburetor. 

One of the tubes extends further into the fuel tank (about 3 inches off the bottom of the tank), while the other is shorter (about 0.5 inches off the bottom of the tank); the shorter tube is the reserve.

While running on the “ON” position of the fuel petcock, your motorcycle will be using the longer metal tube for pumping fuel to the carburetor.

When the fuel gets too low, you will be notified by the low-fuel light on your dashboard. This is when you should switch to the “RES” position of the petcock.

The reserve position means that you will be now using the shorter tube, which is usually a few inches shorter, thus allowing you to use some of the remaining fuel, which falls below the main tube.

It is also worth noting that part of the fuel in your fuel tank will be unusable; the amount will vary from motorcycle to motorcycle and should be stated in your user’s manual.

Why is motorcycle reserve necessary?

The need for a reserve goes back to the years when motorcycles didn’t have low fuel gauges. What happens, in this case, is that once the motorcycle starts to lose power, the rider will simply switch to the reserve and look for a place to fill up their fuel tank. On the reserve, you should typically get between 20 to 50 miles.

And even when a motorcycle has a fuel gauge, the reserve is still a helpful safety net that can be used. Fuel gauges on motorcycles are not reliable and highly dependable on other factors.

Thus you can easily be left with the impression that you have more fuel than what you have, in which case the reserve can be the difference between riding and pushing your motorcycle to the next gas station.

In fact, it is not a stretch to say that on some motorcycles, the only times the fuel gauge will be correct is either when the fuel tank is completely full or completely empty.

In other words, the reserve is there just to tell you that you need to refill your motorcycle fuel tank.

Read next: Can you overfill a motorcycle gas tank?

What happens if you run a motorcycle on reserve all the time?

Running on reserve all the time is not bad for the motorcycle. However, when you run out of fuel, it will mean that you are really out of fuel, and you will have to push your motorcycle to the next place where you can fill it up.

This is the only downside to running a motorcycle on reserve all the time. You will not have that safety net warning that will let you know the fuel is getting low, and you have to fill the tank. Once you feel that stutter, you will have between 20 to 50 miles left in the tank once you switch to reserve.

However, if you are already running on reserve when you feel the motorcycle losing power, it is already too late as the fuel is getting too low for it to run.

If you want to run your motorcycle on reserve all the time, then it is recommended to reset your odometer every time you go for a ride. Learn how far you can go on a full tank of gas. Keep track of how much fuel you have left in the tank and how many miles you can go before having to refuel.

Should you run the motorcycle on reserve all the time?

Some riders who have never run their motorcycle on reserve may wonder if it will be a good idea to do it all the time. You don’t have to run your motorcycle on reserve all the time. However, it is good practice to run it on reserve occasionally.

Here’s the thing.

You should occasionally run your motorcycle on reserve. Running on reserve from time to time will allow you to use fuel that is in the lower part of the fuel tank.

And the lowest parts of the fuel tank is where dirt and water tend to accumulate over time. If the reserve is never used, the dirt, crud, and water can start to slowly accumulate and build up until they reach the level of the reserve or even the main fuel line.

The situation can be particularly bad, and the tank may require more frequent maintenance if the motorcycle is left outside.

More information you can find in my articles about whether leaving a motorcycle outside is OK and whether rain will damage a motorcycle.

By using the reserve, you will prevent water and dirt from building up too much and clogging up the carburetor and fuel lines. The fuel filter should take care of any sediments in the fuel, so you may have to change it frequently.

That being said, to really remove the dirt and water from the lowest parts of the fuel tank, the whole fuel tank should be regularly removed and completely drained and cleaned.

Another thing worth noting is that sometimes it may be worth switching to the reserve when the fuel is getting dangerously low.

This will prevent your motorcycle from sputtering or shutting off at the wrong time, while riding at high speed on the highway, for example. (Make sure to practice switching to reserve so that you can build the muscle memory to do it while riding.)

However, make sure to stop and fill up your motorcycle’s fuel tank before you run out of fuel.

Read next: How often do you have to fill up a motorcycle?


  • Can I run my motorcycle on reserve all the time?
    • This question addresses the concerns riders might have about constantly using the reserve setting on their motorcycle. It explains that running on reserve is not harmful to the motorcycle and is actually recommended occasionally. However, it also highlights that relying on reserve all the time means running out of fuel when the motorcycle is on reserve.

  • How does the reserve on a motorcycle work?
    • This question explains the functionality of the reserve tank on a motorcycle, dispelling misconceptions and clarifying its operation within the main gas tank. It also touches on the significance of the reserve as a safety net.

  • What happens if you run a motorcycle on reserve all the time?
    • This question addresses the potential consequences of consistently running a motorcycle on reserve. It clarifies that doing so is not detrimental to the motorcycle but emphasizes the importance of knowing when to switch to reserve and the potential downsides of relying on it without monitoring fuel levels.
Simon Dufour

Meet Simon, the 46-year-old aficionado behind YourMotoBro. With a lifelong passion ignited by motocross dreams and a Canadian Tire bicycle, Simon’s journey has been nothing short of extraordinary. From coaching underwater hockey to mastering muddy terrains, he’s an authority in thrill and adventure. Certified as an Off-Road Vehicle Excursion Guide and trained in Wilderness First Aid, Simon’s love for bikes is as diverse as his collection—from a robust BMW GSA R1200 to the memories of a Harley Davidson Night Train. By day a respected telephony consultant, by night a motorcycle maestro, Simon’s tales are a blend of expertise, resilience, and undying passion. 🏍️✨