How to Fix Low Compression on Jet Ski

A jet ski is a type of personal watercraft that was invented in the 1960s. A popular activity for many people, Jet Skiing has been used as a form of recreation and military purposes. There are two types of jetskis- those with an enclosed cockpit or open bow. The first opened up to let the rider have more freedom while riding it, and some riders want to feel the wind on their face. The other type protects from waves and splashes because it is closed off from them, so you don’t get wet while riding it.

How to Fix Low Compression on Jet Ski

Low compression on a jet ski is when the engine of your jet ski suffers from too little pressure in its cylinders. This means it will not be able to generate enough power, and thus makes the performance of your watercraft slow or sluggish. A low-compression problem is usually caused by leaks in either the piston rings or valves; this results in high exhaust emission and oil consumption. Today I will be discussing some techniques on how to fix low compression on jet ski. 

Summary: If you are experiencing low compression on your Jet Ski, there are a few things you can do to try and fix the issue. First, check the air pressure in your tires. If they are under-inflated, the air won’t be able to get into the engine as well, which will cause the compression to decrease. Next, make sure the oil level is correct. If the oil isn’t level, the engine will suffer from decreased compression. Finally, make sure that the spark plugs are properly installed and firing. A misfire in the spark plugs can cause the engine to lose compression.

How to Determine Whether My Jet Ski Has Low Compression?

There are certain ways that you can tell if your jet ski has low compression:

  1. When it enters the water, the wave will be taller than the board:
  2. When you start the jet ski, if it is puttering:
  3. If when you are riding at a higher speed than normal and suddenly slow down, and there is no loss of power for the motor.
  4. If your jet ski operates normally on one tank of gas but then starts to sputter out after that, one tank is empty.Normally-Runs-in-Cool-Water-but-Not-in-Warm-Water-1024x512
  5. If your jetski normally runs in cool water, but not in warm water.
  6. There will be less of an arch in the wake behind the Jet Ski;
  7. There will be more air bubbles coming from underneath (exhaust);
  8. It may sound different – like a higher-pitched noise instead of a lower one;
  9. You’ll see increased air being blown out from underneath (exhaust).  

How Harmful is Low Compression for Jet Ski?

Many factors contribute to the engine’s performance on a jet ski. For instance, an old or low-rated battery will not produce enough voltage for it to start on its own. A dirty air filter blocking the flow of oxygen in the tank can also hamper your engine from running continuously. We are one of the largest suppliers of aftermarket parts in the US. We carry a wide range of high-quality OEM and aftermarket parts for PWCs from different brands.

Compression Level of Your Engine

The most important factor is probably the compression level of your engine, which dictates how smoothly and efficiently it runs. Of course, every car or jet ski enthusiast knows this. However, some people still fail to understand why a low-compression ratio is detrimental to a vehicle’s overall performance. A low compression ratio means that your engine will have a lower volume of air and fuel to burn, which can affect its output. Additionally, it can lead to increased fuel consumption and emissions, as well as decreased torque and power.

.If your compression level was too low, you’ll surely notice some signs like rough idling, hard starting, and getting worse gas mileage. Other than that, the overall engine performance will be affected as well. For example, if you have less power to accelerate or you can’t go as fast up hills or boat ramps. In fact, a vehicle with a poorly performing engine usually ends up being thrown away after a few years of service due to its poor quality and mechanics, even though it is still within the warranty period.

A Process on How to Fix Low Compression on Jet Ski

  1. Clean all of the parts that you remove from your engine and carburetor; this will be easier if you lay everything out in their respective place before removing them. Any dirt or grease on these components can keep them from working properly, so clean them thoroughly before assembling. Pay close attention to any areas where the rubber meets metal or air enters the jet ski’s body, as these are typically entryways for water. If a part is damaged beyond repair, replace it with a new one. Use pliers when handling any small nuts or bolts, carefully turning them to remove them from their respective sockets without bending or breaking them. Remove any rubber o-rings from the jet ski carburetor and clean those as well, replacing any broken or worn out.
  2. Disassemble the Carburetor by removing all of the screws on each part of it with a screwdriver; this will enable you to take it apart completely.
  3. Clean the inside of your engine and carburetor thoroughly, paying special attention to areas where air enters and exits the shell; that is typically how water enters, too, so keep these areas free of dirt and grime.
  4. Use a new gasket when reassembling your engine; they come in sets at most marine supply stores or can be purchased separately. Always replace rubber o-rings when you reassemble components, and make sure to avoid pinching any wires while putting your engine back together.Use a New Gasket
  5. When you have all of your components back in their proper place in the carburetor and engine, you’ll need to adjust them according to the manufacturer’s recommended settings: choke level, air/fuel mixture ratio, and idle speed. Again, consult your jet ski user manual for these settings if they are not printed on a sticker inside the carburetor compartment.
  6. Start your jet ski and test its performance after addressing issues with its compression; it should run smoothly now that all parts are clean and properly adjusted, but only testing it will tell you for sure.

Aside from learning how to fix low compression on jet ski, it is necessary to have an idea about the common issues regarding this aspect. The most common problems related to low compression in a jet ski are the following:

A. Intake Gasket Leakage or Cracked

If you find bubbles at the surface of the water, the chances are that there is air entering through an intake gasket leak or crack, which is causing the low compression on your jet ski. You need to fix this problem by replacing the intake gaskets and/or fixing cracks, if any, to resolve this issue. What causes bad compression on a jet ski? The major reason for low compression in the jet ski is an intake gasket leak or crack.

B. Air Filter Assembly- Improper Installation

If you find that your vehicle has many air filters assembly issues such as holes, cracks, and loose bolts, then it may be because of improper installation. Scope out for any such possible issues so that these issues don’t cause any further damage. You can also find some air filters assembly issues if the top and bottom parts of the filter are not properly secured.

C. Water in the Crankcase

If you find that there is water in your crankcase, then it is possible that the breather hole might not be working properly, or it may have been clogged, and this could be causing the low compression on your jet ski. You need to fix this problem by cleaning up the breather holes to be free of any contaminants. If left unattended for a long time, these contaminants can cause corrosion within the engine compartment, which will eventually result in a total system failure. The best way to clean up these holes is to use a wire brush and follow it with an air gun to remove all dirt and debris accumulated inside them.

Water in the Crankcase

The above-listed reasons are the most common causes of low compression on a jet ski, and you need to address each one of them accordingly to resolve this issue. In addition, make sure that you use new bolts while repairing or replacing any part since the old bolts might not hold up against pressure which will cause further damage leading to total system failure. Before you replace any parts, however, make sure that the bolts are secure and tightened appropriately. Another cause of low compression is spark plug fouling, and you need to clean the plugs periodically to prevent it from happening.


In conclusion, I hope that the process mentioned here will help you learn properly how to fix low compression on jet ski. Maintain proper safety while performing the task. Have a nice day.

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Jennifer Branett
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