How To Fix Low Compression On ATV

So your ATV is not starting and making strange noises like never before? You may be running through a low compression problem. Don’t worry as here we brought the solutions for you. We will guide you on how to fix your ATV low compression. Also, we will explain what causes low compression on ATV so you don't get stuck with it in the future. Let’s begin!

The signs of low compression

atv in mud

What are the signs of low compression? Gas leaks from the piston usually cause low compression in an ATV. Your ATV’s engine might not start. If it starts, it may make strange noises. Or it could have low power.

Other signs include leaks in inner valves. The spark plug might be oily; it should be dry. These are what happens if compression is low. You have to look for these signs.

What causes low compression in ATV?

measure compression in atv

Learning what drives a low compression to your ATV will help you to avoid any future risks. Here’s a small list of the causes:

  • You have a faulty or broken spark plug.
  • You may have any malfunctioning or broken inner valves.
  • Piston rings have worn out or been damaged.
  • The head gasket is in bad condition.

If you see any of these, then it is a low compression problem. Otherwise, you may need to observe other issues.

Keep all essential tools and basic spare parts on board. Whether you prefer a bag or a backpack, opt for waterproof storage options.

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You can check the low pressure with a pressure gauge. Please be sure to remove all the spark plugs and deactivate the ignition coil. Attach the pressure gauge in the place of the spark plug. Hold on to the throttle and record the maximum reading in the gauge.

There is low compression if it gives a reading lower than average (more on that later in the article). Now you need to fix it accordingly. Read till the end to know how you can solve each problem.

Solutions to each problem

Now we will discuss how to fix low compression in each case. Make sure to identify your situation and choose the solution as per your issue.

atv spark plugs

The spark plug is broken

A spark plug ignites the combustion in an internal combustion engine. If the spark plug broke or got damaged, you either lose the compression or get no compression at all. If the spark plug breaks down, it won’t ignite the small explosion to move the piston.

If it is malfunctioning, you can easily remove and place it back. It will help you in getting the spark. But if it is broken, then you will need to replace it. A faulty spark plug is among the significant causes of low compression.

You need to remove or replace it. Unfortunately, you can’t check which one is causing the problem. You need to replace them all. Spark plugs are inexpensive so they won't put much stress on your pocket.

But sometimes, the reinstallation of them is enough.

broken atv valves

Inner valves are broken

Another major cause of low compression is broken or defective inner gas valves. If the valves are damaged, the gas may leak from them.

Gas may also leak from inner valves if their opening and closing time is not synchronized. It is due to the loosening of springs. The valves do not sit in their place properly, or they overheat so much that it wears out their seals. So check those air intake and exhaust valves.

In each case, you have to check every piston. The only way to fix it is to replace it. You need to replace the valve which is causing the gas leak.

atv piston rings worn
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Piston rings have worn out 

Two to four piston rings are around each piston to seal the air in the ignition chamber. Their purpose is to keep the crankcase and the combustion chambers material separated. Worn out or damaged piston rings let the gas or the fuel enter the crankcase.

It may also result in the leaking of oil into the combustion chamber. Both cases cause low pressure. Do a compression test to check it. If you find a leak, there is a makeshift remedy. You can pour some diesel into the cylinder.

Leave it there for some time. Then do a pressure test. It may solve the issue. But if you still find the leak, replace the rings or the piston immediately.

broken head gasket

The head gasket is in bad condition

A faulty head gasket causes the shift of compression to coolants or the other leaks. The head gasket ensures that every part gets its proper pressure. But a worn-out one will make pressure differences.

A pressure test can point out a bad gasket. If you are observing low compression on adjacent pistons, then the culprit is the gasket.

Other signs you can check are white smoke coming out of the exhaust pipe. The engine is overheating and too noisy. Spark plugs are getting damaged every short time. You may also observe the coolant leaking from the engine.

You can fix it, again, by replacement. But you need to take out the whole engine. It can’t be done without it.

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What is the lowest compression for ATV?

atv rider

Mostly a question is asked: will ATV run with low compression? The minimum requirement to run an ATV is 100 PSI. It needs at least 100 PSI to function well. So if it is below the limit, then the sweet answer is, No.

And most ATVs run on a maximum pressure of 250 PSI, but some can go up to 300 PSI.


atv riding in water

Now you know how to check any problem that is caused by low compression. And you also know the measures to prevent it. The only catch is that it mostly requires a replacement, and you have to take the whole engine out.

Since now you can identify and fix the problems, your ATV will roar again to its fullest! Are you ready to see how deep you can go?

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