Kawasaki STX-15F Specs and Review [Video]

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The Kawasaki STX-15F was the predecessor of the more advanced STX-160 series. This race-inspired 3-seater jet ski was revealed in 2004 and remained in production until 2020.

If you want to find out more about this machine, you’ve come to the right place.

We at JetDrift have compiled all you need to know into this detailed Kawasaki STX-15F review!

Kawasaki STX-15F Review

Kawasaki STX-15F History

The history of the Kawasaki STX-15F goes back to the early 2000s when the manufacturer introduced its predecessor, the SXT-12F. This machine was released in 2003 to be a high-end 3-seater Kawasaki jet ski powered by a fuel-injected, 4-cylinder 1,199cc engine.

For the next model year, this ski got a more powerful 1,498cc engine option and the STX-15F was born.

Surprisingly, this model had been manufactured from 2004 through 2020 in basically the same form, except for some cosmetic differences.

Even though it was marketed as the flagship Kawasaki jet ski during its first years, it was then demoted to a middle-size and finally to an outdated entry-level model over the decades.

The STX-15F was officially discontinued in 2020, but it lives on in the STX-160 series. The successor family got a new top deck and some advanced features, but beyond these, they remain identical to the STX-15F.

Yes, that’s right, the 17-year-old hull, the 1.5L engine, and the jet pump were all carried over without any significant changes.

Let’s get down to the nitty-gritty and talk about the iconic SXT-15F in detail!

Kawasaki STX-15F Engine

It’s a lesser-known fact that the STX-15F borrowed its engine from the Kawasaki Ninja motorcycle family. However, it was specially redesigned for marine use.

Regarding specifications, the power source of the Kawasaki STX-15F was a 1498cc, DOHC, 4-stroke, 4-cylinder engine.

It featured an open-loop cooling system, fuel injection, electric start, semi-dry-sump lubrication, and a digital transistor ignition system.

Compared to its predecessor, this powerhouse displaced 300cc more, which translated to plenty of torque and a remarkable 160 HP. Thanks to its advanced features and 4-cylinder in-line configuration, it offered a smooth power delivery in all RPM ranges.

Engine power was transferred to a 148mm, axial-flow, single-stage jet pump generating a maximum thrust of 955 pounds (4,250 N).

Besides its great performacne figures, this engine was also known for its moderate noise and low emissions.

This was not surprising since the STX-15F was designed to meet all current environmental regulations, including the standards set by the U.S. Environmental Protection Agency and the more rigorous Air Resources Board standards of California.

This engine found its way to other popular jet ski models including the 4-stroke Kawasaki SX-R 1500 stand-up ski, the Ultra LX, and the aforementioned STX-160 series.

What’s more, the high-performance power source of the flagship Ultra 310 series is virtually a supercharged and intercooled configuration of the STX-15F engine.

Unlike its supercharged brothers, the STX ran on 87 octanes.

Kawasaki STX-15F Hull

According to the manufacturer, the SXT-15F inherited its hull from the predecessor world championship-winning 1200STX-R racing jet ski.

This race-inspired platform was made of Fiberglass Reinforced Plastic (FRP) and measured 122.8 inches in length, 46.5 inches in width, and 43.1 inches in height. The curb weight of the ski was 845 pounds while its load limit was 496 pounds including riders and cargo.

Compared to the rival Yamaha VX and the Sea-Doo GTI 155 SE, the Kawasaki was significantly heavier but slightly shorter.

Its top deck was dressed in Kawasaki green and featured a 2-piece seat rated for three riders.

The total storage capacity of the ski was 23.5 gallons, split into a glovebox, a standard bow storage compartment, and a small storage bin under the rear portion of the saddle.

While its design was fresh at the time of its introduction, it became fairly outdated over the years.

Kawasaki STX-15F Features

Riders agree that the main drawback of the STX-15F was the absence of a brake system. This model was only equipped with a simple mechanical reverse, which could be operated manually.

In contrast, major competitors offered their models with more advanced brake and reverse systems like Yamaha’s RiDE, and Sea-Doo’s iBR.

Its basic manual reverse and an outdated look made the Kawasaki less appealing in the marketplace than the competitor GTI and VX models.

Standard features of the Kawasaki STX-15F included:

  • Multi gauge
  • 5-gallon storage capacity
  • Glovebox
  • Small rear storage bin
  • 4-gallon fuel tank
  • Sponsons
  • Dual mirrors
  • Mooring cleats
  • 2-piece seat for 3 riders
  • Tow hook
  • Reboarding step
  • Learning “SLO” key

Kawasaki STX-15F Riding Experience

The STX-15F was known as a dependable family jet ski, yet powerful enough for thrill seekers.

It offered significantly more engine power than its competition, translating to an industry-leading acceleration and speed in the non-supercharged segment.

Under ideal conditions, the STX-15F could do the 0-30 run in 2 seconds while its top speed was 60-62 mph on GPS. However, its inaccurate paddle wheel speedometer often showed 65-67 mph.

Thanks to its race-intended hull, the ski was very nimble and offered a great overall riding experience.

According to The WaterCraft Journal, the STX-15F stayed hooked and could cut through a mild chop with ease.

Sadly, on bigger waves, the ski started to suffer due to the relatively flat hull design.

It wasn’t as stable and predictable as the deep-V hulls of the flagship Ultra family, but it offered adequate stability and performance even with three riders.

Thanks to its easy handling and roomy top deck, the STX was very popular among families and beginner riders. A learning key (a.k.a. Smart Learning Operation “SLO”) came with the ski as standard, designed to tame the engine performance for novice riders.

Based on our research the pros of the STX-15F were as follows:

  • Great power-to-weight ratio.
  • Proven, reliable construction and features.
  • Reasonable fuel efficiency.
  • Handled flat and mid-chop water conditions well.
  • Easy and cheap to maintain.

And the cons:

  • Its flat hull couln’t effectively handle bigger waves.
  • Became nose-heavy on a full tank of gas.
  • Burped a lot while fueling.
  • The low fuel warning came on too soon.
  • The bow storage was hard to reach on the water (this is a common problem in its class).
  • The rear portion of the seat had to be removed to access the engine.
  • The seat was a little hard compared to other models.
  • Outdated design.

Kawasaki STX-15F Specs Chart

For your convenience, we’ve compiled the key specifications of the Kawasaki STX 15F into these charts (2018 model):

Kawasaki STX-15F Engine Specs

EngineKawasaki STX-15F
Type4-stroke, 4-cylinder, DOHC, 4-valve, water-cooled
Displacement1 498 cm³ (91.4 cu in.)
Bore x Stroke83 × 69.2 mm (3.27 × 2.72 in.)
Compression Ratio10.6 : 1
Ignition SystemDigital transistor
Lubrication SystemSemi-drysump
Fuel SystemDigital fuel injection
Antiknock Index ((RON + MON)/2)Minimum Rating 87
Starting SystemElectric starter
Engine Oil TypeAPI SG, SH, SJ, SL or SM with JASO MA, MA1 or MA2
Engine Oil ViscositySAE10W-40
Engine Oil Capacity5.0 L (5.3 US qt)
Battery12 V 18 Ah (10 HR)

Kawasaki STX-15F Tuning Specs

Tuning SpecificationsKawasaki STX-15F
Spark Plug NGK CR9EKB
Spark Plug Gap0.7 - 0.8 mm (0.028 - 0.032 in.)
Spark Plug Terminal Solid post terminal
Ignition Timing3° ATDC @1 300 r/min (rpm) - 32° BTDC @3 000 r/min (rpm)
Idle Speed - in water1 300 ±100 r/min (rpm)
Idle Speed - out of water1 300 ±100 r/min (rpm)

Kawasaki STX-15F Drive System

Drive SystemKawasaki STX-15F
CouplingDirect drive from engine
Jet Pump - TypeAxial flow, single stage
Jet Pump - Thrust4 250 N (434 kgf) (955 lb)
Steering Steerable nozzle
Braking Water drag

Kawasaki STX-15F Performance

PerformanceKawasaki STX-15F
Minimum Turning Radius4.0 m (13.1 ft)
Fuel Consumption43 L/h at full throttle (11.4 US gal/hr)
Cruising Range134 km at full throttle (83.3 mi - 1 hr and 26 min)

Kawasaki STX-15F Dimensions

DimensionsKawasaki STX-15F
Maximum number of riders3 persons (1 operator and 2 passengers)
Load Limit225 kg including riders and cargo (496 lb)
Overall Length 3 120 mm (122.8 in.)
Overall Width 1 180 mm (46.5 in.)
Overall Height 1 050 mm (41.3 in.)
Curb Weight 383 kg (845 lb)
Fuel Tank Capacity 62 L (16.38 US gal)

These charts are for informational purposes only! For exact specifications, please refer to the factory manual.

Takeaways

As a takeaway, we’ve answered the most common questions about the Kawasaki STX-15F!

What is a Kawasaki STX-15F?

The STX-15F was a 3-seater sit-down jet ski manufactured by Kawasaki.

When did the SXT-15F Come Out?

The Kawasaki STX-15F debuted in late 2003 for the 2004 model year.

What Years Did Kawasaki Make the SXT-15F?

Kawasaki marketed the STX-15F from 2004 through 2020.

What Size was a Kawasaki STX-15F?

The Kawasaki STX-15F measured 122.8 inches in length, 46.5 inches in width, and 43.1 inches in height, while its maximum draft was 14.6 inches.

How Much Did a Kawasaki STX-15F Weigh?

The dry weight of the Kawasaki STX-15F was 732 pounds, while its curb weight was 845 pounds.

How Much Weight Could a Kawasaki STX-15F Carry?

The load capacity of the Kawasaki STX-15F was 496 pounds including riders and cargo.

What Size Storage Compartment Did the STX-15F Have?

The total storage capacity of the SXT-15F was 23.5 gallons, split into a bow storage, a glovebox, and a small storage bin under the rear seat.

How Many People Could Ride on a Kawasaki STX-15F?

The Kawasaki STX-15F could carry 3 adult riders with ease.

What Kind of Engine was in the Kawasaki STX-15F?

The Kawasaki STX-15F was powered by a 4-stroke, fuel-injected, 1498cc, 4-cylinder Kawasaki engine.

Was the Kawasaki STX-15F Supercharged?

The Kawasaki STX-15F utilized a naturally-aspirated engine.

Was the Kawasaki STX-15F a 4-stroke?

Yes, the Kawasaki STX-15F was powered by a 4-stroke engine.

How Much Horsepower Did a Kawasaki STX-15F Have?

The Kawasaki STX-15F produced a remarkable 160 HP.

What Oil Did a Kawasaki STX-15F Use?

According to the owner’s manual, the Kawasaki STX-15F used SAE10W-40 engine oil (API SG, SH, SJ, SL, or SM with JASO MA, MA1, or MA2).

How Much Oil Did a Kawasaki STX-15F Hold?

The oil capacity of the Kawasaki STX-15F was 5.3 US quarts (5.0 L).

How Much Fuel Did a Kawasaki STX-15F Hold?

The Kawasaki STX-15F was equipped with a 16.4-gallon fuel tank.

How Much Fuel Did a Kawasaki STX-15F Use?

The fuel economy of the Kawasaki STX-15F was about 11.4 GPH at WOT.

What was the Fuel Range of the Kawasaki STX-15F?

Considering its 16.4-gallon fuel tank and the fuel economy of 11.4 GPH, the estimated fuel range of the STX-15F was about 80-90 mile, which equals 1 hour and 26 minutes of riding time. However, don’t forget that this was just a theoretical number as you should always leave 1/3 of the fuel in the tank for safety reasons.

How Fast Did a Kawasaki STX-15F Go?

The top speed of a Kawasaki STX-15F was about 60-62 mph on the GPS (more like 60-67 mph on the speedometer).

Did the Kawasaki STX-15F Have Reverse?           

Yes, the Kawasaki STX-15F came with a mechanical reverse.

Did the Kawasaki STX-15F Have a Brake?           

No, the Kawasaki STX-15F was manufactured without a brake.

Did the Kawasaki STX-15F Have Speakers?

The Kawasaki STX-15F was marketed without speakers.

Could the STX-15F Tow a Skier or a Wakeboarder?

Yes, the Kawasaki STX-15F could tow a skier or wakeboarder with ease.

How much does a Kawasaki STX-15F cost?

The asking price of used Kawasaki STX-15Fs varies between $4,000 and $9,000 depending on the year and its condition.

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