Old Gas In Your Motorcycle: How Long Does It Take For The Gas To Become Bad And Related Issues

I. Introduction

As motorcycle riders, we all must have faced the issue of old gasoline in the tank at some point in time. Fortunately, with little extra knowledge, this issue can be handled safely.

This article discusses the following issues:

II. How long does it take for the gasoline in your motorcycle to go bad?

Many of us assume that the gasoline in our motorcycle tank will not go bad even if it is left unused for long periods. This is not true.

The gasoline sold in the USA is not pure, it is gasoline and 10% ethanol or ethyl alcohol (please see https://www.eia.gov/tools/faqs/faq.php?id=27&t=10). Ethanol is mixed with the gasoline to make it burn completely and emit less polluted fumes. Gasoline blended with ethanol can have a shelf life of up to 3 months because ethanol reacts fast with oxygen to get oxidized and it can also absorb moisture from the air. The motorcycle tank has both leftover gasoline and air in it, so the gasoline can easily absorb moisture in the air.

Also, gasoline has a property called volatility and this makes it form vapors at a slow rate, something which also helps quick start your motorcycle. This vaporization continues even when the motorcycle is lying idle. Over the period, vapors formed are lost and the combustibility quality of the gasoline deteriorates.

After 30 days, the gasoline can be contaminated with water and can separate into gasoline and ethanol layers. So, the gasoline left in your motorcycle tank can start losing its quality gradually and can start becoming bad after a month. Over time, gum formation can happen.

To summarize, the deterioration of the gasoline starts after 30 days if you do not use your motorcycle and top up the old gasoline with fresh gasoline.

If the gasoline left in your motorcycle tank has a stabilizer mixed in it, the life can be enhanced a little; however, the stabilizer cannot completely stop deterioration.

III. How to know that the gasoline in a motorcycle tank is bad?

Before deciding whether the old gasoline in your motorcycle tank has gone bad or not, you can do some simple tests.

Take a small quantity of the old gasoline from your motorcycle tank and also the same quantity of fresh gasoline and place them side by side in transparent glasses.

Compare the color and appearance of the two samples, and you can also smell them. Old gasoline will smell stale similar to old food. Moreover, old gasoline having solid particles, high water content, decolorized, or gum is an indication of bad gasoline. You should be able to judge the quality of old fuel by these two simple tests.

If you are still undecided, you can try to go for a ride. If the gasoline is bad, the motorcycle may not start, and even if it starts with repeated efforts, the idling will be bad, and you can feel the loss of power during the ride (especially during acceleration).

If the old gasoline is good, it starts quickly and gives you a smooth ride. However, there is a risk in this method. When you start your motorcycle and the gasoline is bad, you are doing the mistake of allowing it to enter the carburetor or fuel injection system and clog them.

IV. What happens if you ride your motorcycle with old gasoline?

The first issue can be your motorcycle not starting at all since the gasoline has lost its ability of combustibility.

The second issue is that if you ride or attempt to ride your motorcycle with bad gasoline, it can damage the internal parts of the engine, such as the carburetor or the fuel injection system. The gum in the bad gasoline can clog the jets and valves of the carburetor. This adds to the repair cost.

Hence, if you have left your motorcycle for a long period with gasoline in the tank, the best thing to do is to inspect the old gasoline and even if you have a slight doubt that it is bad, drain it off completely and fill fresh gasoline after cleaning the tank. You also have to drain the old gasoline from the carburetor and the carburetor float valve and jets may need cleaning as well.

You may also change the fuel hose line and fuel cock, they may not cost much.

V. How to drain out old gasoline from your motorcycle tank?

There are three ways to do it.

  • Drain out the bad gasoline from your motorcycle tank by simply removing its connection to the carburetor and diverting the gas to a container.
  • Detach the gasoline tank from your motorcycle and drain the bad gasoline from it.
  • Use a siphon pump.

1. Draining the bad gasoline from the motorcycle fuel tank

Do this activity in a well-ventilated area or in the open. Take a good quality can. Turn off the petcock. Disconnect the hose from the carburetor that connects it to the petcock and place it inside the can.

There can be some gasoline in the hose and it can spill out, so place a waste cloth there. Turn the petcock on and drain the old fuel. If your gasoline tank has a section for reserve fuel, drain that as well. The old gasoline drains out due to gravity.

2. Detaching the fuel tank

If you have experience and are conversant with removing the fuel tank from the motorcycle, you can detach the gasoline tank from the motorcycle and then drain out the old gasoline.

3. Use a siphon pump

If you have a siphon pump (or you can buy it), you can use it to drain the old gasoline directly from the fuel tank. A siphon pump has two hose lengths placed on either side of the small pump. Push one end of the hose into the fuel tank through the cap hole (ensure the hose touches the bottom) and place the other end of the hose in the can. Operate the siphon pump slowly till you drain the tank completely.

Note: After the old gasoline is drained, it is better to clean the gasoline tank to take out any traces of bad gasoline. The carburetor also needs complete cleaning.

VI. If your motorcycle has old gasoline problems, can the motorcycle be repaired?

Yes, definitely. Your motorcycle has only gone bad, not ruined.

The bad gasoline in your motorcycle might have clogged the jets and valves of the carburetor. Take the help of your mechanic. The mechanic can drain out the old gasoline completely from the gasoline tank, clean the gas tank, clean and rebuild the carburetor and bring your motorcycle to its original condition.

It is better to replace the fuel hoses, fuel filter, and petcock as well.

VII. What preventive actions you can take to avoid issues relating to old gasoline in your motorcycle?

  • If you have planned to store your motorcycle in your garage for a longer period, the best thing is to drain off the gasoline from the motorcycle gas tank and carburetor and close the tank securely with the cap.
  • If you are storing your motorcycle for a month or two, it is better to take a short ride once a week or fortnight to avoid fuel stagnation. If you cannot do this yourself, one of your family members or friend can help you. This will minimize the chances of gasoline turning stale after one month.
  • You can take the advice of your mechanic and add a recommended stabilizer to the gasoline. After adding the stabilizer, turn on the motorcycle for a few minutes so that the stabilizer enters the complete fuel line. However, a stabilizer can only delay the deterioration of gasoline, it cannot stop it.
  • If your usage of the motorcycle is not regular and the gap between two rides can be more than a month, then it will be good if you use the gasoline mixed with a good stabilizer and always top up with fresh gasoline when you use it next time. This will keep the gasoline in the tank in good condition.

VIII. Frequently asked questions (FAQ)

1How can I know that the old gasoline sitting in my motorcycle tank is good or bad?
Take a small quantity of the old gasoline from your motorcycle tank and also the same quantity of fresh gasoline and place them side by side in transparent glasses.

Compare the color and appearance of the two samples, and you can smell them as well. As old food smells stale, old gasoline will also smell stale. Old gasoline having solid particles, high water content, decolorization, or gum is an indication of bad gasoline. You should be able to judge the quality of old fuel with the help of these two tests.

If you are still undecided, you can try to go for a ride. If the gasoline is bad, the engine may not start, or even if it starts the ride will not be smooth. If the old gasoline is good, it starts quickly and gives you a smooth ride.

2What is the shelf life of gasoline?
Gasoline stored in a sealed container at a cool and dry place can have a shelf life of up to 3 months and the deterioration can start earlier than three months. However, gasoline stored for more than 6 months may not be good to use.
3Can I mix old gas with new gas?
Yes, you can mix old gas with new gas. However, you have to ensure that the old gas has not gone bad.
4What care I can take when storing the motorcycle for long period?
If you are storing the motorcycle for more than 2 months, the best thing to do is drain out the gasoline from the fuel tank as well as the carburetor, and securely close the fuel tank with the cap.

Alternately, you can add a stabilizer and run the engine for a few minutes so that stabilizer reaches the complete fuel line. However, a stabilizer can only delay the deterioration of gasoline, it cannot stop it.

5What happens if I ride my motorcycle with bad gasoline?
If the gasoline has gone bad, your motorcycle may not start, and even if it starts the ride will not be smooth. To bring your motorcycle back to riding condition, you have to drain the bad gasoline from the fuel tank and get your carburetor serviced/rebuilt by your mechanic.

IX. Conclusion

The above discussion makes it clear that the issue of old gasoline in a motorcycle tank can be handled safely by taking some easy preventive measures before storing the motorcycle for a longer period.

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