Is It Normal for a Jet Ski To Smoke ?

Jet skis are a great way to spend hours out enjoying yourself on the water. Whether you use your jet ski in the sea or a lake, you’re guaranteed a good time. However, jet skis can be difficult to maintain, and they’re prone to smoking while in operation.


It is normal for a jet ski to smoke during operation if it has a two-stroke engine. However, jet skis with four-stroke engines shouldn’t produce smoke during the normal process. If your four-stroke jet ski smokes, that means it has operational issues.


Keep reading to learn more about what causes jet ski engine smoke, how you can prevent your jet ski from smoking, and how you can seafoam your jet ski. By the end of this article, you’ll better understand how your jet ski works and how you can adequately maintain your jet ski.

It’s Normal for a Jet Ski To Smoke

Jet skis smoke under a typical operation if they are operating using a two-stroke engine. This happens due to the internal combustion process that two-stroke oil undergoes when inside the engine.


Jet skis may also smoke when they operate using a four-stroke engine; however, this is not normal. If a four-stroke engine smokes for more than a couple of seconds, it’s likely due to a severe issue developing in the mechanism.

Common Causes of Jet Skis Smoking

Jet skis smoke for a wide variety of reasons. Your jet ski’s smoke may be an indication of a severe issue or nothing at all, depending on your jet ski’s engine and the color of the smoke. The following explains common causes of jet skis smoking:

There’s Water in Your Jet Ski’s Fuel

Harmful gas is a common source of issues in jet skis. The problem happens when water gets into the fuel in the jet ski, usually due to the vehicle being left idle. When this happens, the engine will operate poorly and produce a cloud of white or grey smoke. Bad gas will significantly damage the jet ski’s performance. You’ll likely need expert help to repair.

The Jet Ski’s Gasket Head Is Damaged

Damaged gasket heads are another prevalent issue in jet skis, causing them to smoke. The gasket head is a vital jet ski engine that keeps coolants and oil leaking into the cylinders. If this piece fails, your jet ski engine can be severely damaged and require professional repair

There Are Fuel Injector Issues

Fuel injectors are a hard-working part of your jet skis engine. However, they’re prone to the buildup of dirt over time. It can lead to blockages or misfires within the machine. Fuel injection issues are common, although there’s a straightforward solution to this issue using SeaFoam.


Sea Foam SS14 Cleaner and Lube is a product available on Amazon. You can purchase this liquid to clean your engine and remove any blockage. It is oxygen-sensor safe.

The Jet Ski Hasn’t Been Used in a Long Time

Jet skis that have been in storage for a few months will more than likely produce white smoke when they’re first used again. This smoke is usually water vapor escaping from the exhaust, as cool water evaporates when it comes in contact with the hot exhaust. The steam shouldn’t last for very long and is not a cause of concern.

Your Jet Ski Has a 2-Stroke Engine

2-stroke engines produce smoke while operating, unlike four-stroke engines where smoking indicates an issue. That’s due to the combustion process in a two-stroke engine that burns oil. When the oil is burned, the vehicle’s exhaust expels dark blue or black smoke.

What Happens if You Put Too Much Oil in a Jet Ski?

Jet skis can be difficult to operate without the proper knowledge and experience. One aspect of maintaining jet skis that owners often struggle with is pouring too much oil into the vehicle. However, some people are unsure what happens if they put too much oil in their jet skis.


The jetski will produce a distressing amount of smoke if you put too much oil in it. Too much oil in your jet ski will also prevent it from running for long periods, and it can cause damage to the engine over time, resulting in the need for expensive repairs.


Putting in too much oil is only an issue for jet skis with four-stroke engines. This is due to the combustion differences between 2 stroke and four-stroke engines. Typically, running a four-stroke engine with too much oil won’t cause significant damage to the engine unless it happens for a long time.


When a four-stroke jet ski has too much oil, it won’t expel smoke from the vehicle’s exhaust. Instead, the smoke will bellow out the sides of the jet ski. If you don’t know why this is happening, it can be a very worrying sight for the rider and anyone else nearby.

Seafoam Your Jet Ski To Maintain Its Fuel Injectors

SeaFoam is an effective way of preventing issues with fuel injectors in jet skis. Dirty or damaged fuel injectors commonly cause problems in jet skis and produce smoke. To save money on bringing your jet ski to a shop for SeaFoam, you quickly do it yourself with little experience or expertise required.


To add SeaFoam to a two-stroke jet ski engine, mix 2 oz (59.15 mL) of Seafoam to each gallon of oil you use to clean a dirty machine or fuel Injector. However, if you wish to maintain your engine regularly, you only need to add 1 oz (29.57 mL) of SeaFoam to every gallon of fuel that you use.


Seafoam causes old oil to return to a liquid state in the engine. It causes build-ups of grease and old oil to be cleared from the motor while it’s being used. When the old oil is removed from the jet ski engine, it may produce more smoke than expected; however, this isn’t causing concern as the machine is being cleaned.

Final Thoughts

Jet skis are a fun and adventurous way of traveling over water. However, they can be challenging to keep and maintain. Depending on what engine size your jet ski is, smoking during operation is either a sign of regular use in a two-stroke or a sign of an issue in a four-stroke.


Smoking in a four-stroke engine is most commonly caused by too much oil, damage to the head Gasket, or pool fuel injection. Poor fuel injection can easily be avoided using Seafoam to prevent build-ups of dirt and old oil within the engine.

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