Which Engine Can You Put in a Jet Ski? [Video]

If you are looking for a new engine for your jet ski, the best practice is to use another purpose-built jet ski engine. Car, motorcycle, and boat engines don’t fit into small jet ski hulls, and installing any of them would require too much effort.

Despite this, you can find some jet skis out there with car and motorcycle engines.

If you want to find out more about these machines and the drawbacks of these engine swaps, this post is for you.

We at JetDrift have compiled all you need to know under one roof!

Which Engine Can You Put in a Jet Ski?

Can You Put a Car Engine in a Jet Ski?

Although it is possible to put a smaller car engine into a jet ski, this conversion would be a waste of time and money.

Let’s face it, car engines aren’t designed for marine use, so they would have to be heavily modified to fit into a jet ski.

If you want to put a car engine into your jet ski at all costs, be prepared for a lot of work, since everything would have to be customized.

Why?

Due to their design, the engine and exhaust components of cars are dependent on airflow. Since in a jet ski these systems sit in an enclosed hull, you would have to completely redesign the cooling systems of the engine and the exhaust.

Another big challenge is that you would have to connect the crank of the engine to the pump with a driveshaft.

Also, jet skis feature a gear reduction system instead of a regular transmission. This is why a jet ski engine is continuously spinning the impeller when the engine is on, even in off-throttle situations.

Converting a car transmission into a jet ski-compatible system would also entail enormous work.

Lack of space would be another issue since, unlike car engines, stock jet ski power mills feature a slim design with a low crankshaft position. Car engines and their systems can hardly fit into tiny jet ski hulls.

On top of that, jet ski engines are extremely powerful, ensuring the best power-to-weight ratio. In contrast, car engines generate less HP, so they more than likely couldn’t beat the performance of even an entry-level jet ski.

Keep in mind that car engines have completely different torque curves and RPM limits, so matching them to a jet ski pump would be a challenge as well.

Can You Put a Motorcycle Engine in a Jet Ski?

Due to the aforementioned reasons, a motorcycle engine can also hardly be retrofitted into a jet ski hull.

Even though many production jet skis inherited their engines from motorcycles or other powersport vehicles, each of these power mills is heavily modified.

For example, the Yamaha MR1 is actually a modified R1 Yamaha motorcycle engine, while the Kawasaki Ultra 300 series inherited its engine from the Ninja ZX14 sport bike.

It’s also a lesser-known fact that the Rotax 900 ACE engine of Sea-Doo Sparks comes from Ski-Doo snowmobiles.

But again, even if they have the same origins, these jet skis have vastly different engines than their motorcycle and snowmobile counterparts.

They come with different characteristics, transmissions, cooling systems, exhaust, crankshaft design, and so on.

Consequently, converting a motorcycle engine into a jet ski engine is not as easy as it seems!

Can You Put a Boat Engine in a Jet Ski?

Like car engines, inboard boat engines are also too bulky to fit into a jet ski hull. They are also much heavier and have different features.

Therefore, repowering a jet ski with a boat engine is not a good idea either.

Despite this, some owners attach an outboard motor to their jet ski, which looks like a fun project rather than a “true” engine swap for adequate performance.

Can You Swap Jet Ski Engines?

If you want to repower your jet ski, best practice is to use another stock jet ski engine for this purpose.

You can find many wrecked jet skis with a good engines out there, which are often ‘parted out’ by their owners.

These power sources and jet pumps can be retrofitted into many other jet ski hulls with some fabrication.

Many owners retrofit 4-stroke jet ski engines to fit into vintage 4-seater jet skis like the boat-like Sea-Doo LRV, Polaris Genesis, or the Yamaha SUV.

Since 4-seater jet skis are no longer in production, many of these older machines can be reborn with a new power source.

Conclusion

Repowering a jet ski is never an easy job since these vessels come with special, purpose-built engines.

If you have a jet ski with a broken engine and are looking for an engine swap, you should consider buying another ski instead. You can still sell your current ski for parts or even in one piece.

Note that a jet ski engine swap is a huge, time and money-consuming project.

If you want to repower your jet ski with another engine at all costs, you may want to use another stock jet ski engine.

Other power sources including car, motorcycle, and snowmobile engines come with vastly different features, including the cooling and exhaust systems, crankshaft position, transmission, and more.

Modifying these systems and forcing an inadequate engine into a jet ski is simply not worth the effort.