Snowmobiling is a popular winter activity, and it's essential to ensure your snowmobile is in good working order before hitting the trails. This blog post will discuss how to check compression on a snowmobile. We'll cover the basics of compression and how to test it, as well as some tips for keeping your snowmobile running all season smoothly!

What Is Good Compression On A Snowmobile?

Compression on a snowmobile is important for maximizing performance and engine life. Good compression means the cylinders will use fuel more effectively, and the engine will be able to produce more power. The ideal compression should be between 125 and 130 PSI on most engines. Too much compression can create extra heat in the engine, leading to accelerated wear. 

Keeping your snowmobile at the right compression is essential for achieving excellent performance during the winter season. Likewise, too low of pressure can mean that the pistons are weaker and won't make as much power as they should. To check your snowmobile's compression, you'll need to use a gauge to measure it directly from each cylinder head.

How To Check Compression On A Snowmobile

A proper compression test is a great way to check the overall health of your snowmobile's engine. They measure the amount of pressure created when the piston in an engine is pushed down by the spark plug, and they can be used as a compression gauge for determining how well it’s running. The higher the compression reading, the better condition an engine is usually in.

To perform a compression test on your snowmobile, you’ll need to remove any air filters or obstructions around the spark plugs. You’ll then want to attach your compression tester to the spark plug hole and crank over the engine with a wrench or socket. If your snowmobile has multiple cylinders, perform this step for each one.

Testing compression is best done with the engine cold, but it's possible to do a warm-engine test if needed. Once the engine is cranking, record the pressure reading displayed on the compression tester and compare it to your snowmobile's manufacturer's recommended level. If you have access to a service manual for your model, you should be able to find this information.

If your compression readings are lower than recommended levels, you may have an issue with your snowmobile’s engine, such as worn parts or improper spark plug gap settings. In this case, it would be best to consult a professional mechanic or another knowledgeable individual who can help diagnose the problem and recommend repairs or replacements.

Common Causes Of Low Compression On A Snowmobile

Here are some of the most common causes of low compression on a snowmobile:

1. Worn Or Damaged Rings

The piston rings on a snowmobile engine can wear out over time, leading to low compression and difficulty starting the machine. This is most common in older engines with higher mileage but can also occur in newer machines due to improper maintenance or excessive operating temperature.

2. Stuck Valves

Intake and exhaust valves that become stuck open can cause a decrease in compression, resulting in the poor overall performance of the vehicle. This issue can be caused by debris buildup around the valve stems and worn components like bearings and seals.

3. Incorrect Timing

If a snowmobile’s timing is off, it won’t achieve ideal levels of compression and will suffer from poor performance. This can be caused by incorrect installation of the camshaft or crankshaft and the timing chain.

4. Leaking Head Gasket

A head gasket is responsible for sealing off combustion pressure, so a leak will cause compression loss and reduce engine efficiency. This issue can become serious if not addressed promptly.

5. Blown Cylinder Seals

Cylinder seals are necessary to ensure that the pistons move up and down with optimal compression in each cycle. If these components fail, air can escape without being appropriately compressed, leading to decreased performance.

6. Clogged Air Filter

The air filter is essential to any snowmobile engine and must remain free of dirt and debris for the engine to run correctly. A clogged air filter will restrict airflow, leading to low compression and poor performance.

7. Water In The Cylinder

If water finds its way inside your snowmobile’s cylinder, it can cause a decrease in compression since it does not compress the same way gasoline does. This issue is often caused by flooding or condensation buildup due to humidity.

8. Low Oil Levels

Snowmobiles require oil to function correctly and ensure optimal performance levels. Low oil levels can lead to less lubrication around the pistons and valves, resulting in decreased compression and other issues like knocking noises and excessive wear on internal components. It is important to check and maintain the engine’s oil levels regularly.

How To Fix Low Compression On A Snowmobile

Several different issues can cause low compression on a snowmobile. The most common causes are worn piston rings, worn cylinder walls, and damaged valves. If the problem is left untreated, it can lead to poor engine performance and even catastrophic failure.

To fix low compression on a snowmobile, you will need to do the following:

1. Remove the spark plug from the cylinder head and inspect for any signs of damage or wear.
2. Run a compression test using a gauge or tester to determine how much pressure each cylinder produces. Ensure all cylinders have similar results; further investigation may be needed.
3. Inspect the piston rings for signs of wear or damage, and replace them if necessary. Inspect the cylinder walls for signs of wear or damage, bore them, and hone them as needed to restore compression.
4. Check the valves for any signs of damage or sticking, and replace them as needed.
5. Perform a leak-down test on each cylinder to check for other possible leaks that could be causing low compression.
6. Finally, reassemble everything to factory specifications and repeat the compression tests to ensure all cylinders produce similar results before starting the engine warm again.

Hopefully all that information helps your snowmobile get in tip-top shape for those hills. If you’re looking for more information on snowmobile parts and everything outdoors, make sure you check out LionParts!