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1986-1988 Kawasaki JS300 Review and Specs [Video]

1986-1988 Kawasaki JS300 Review and Specs [Video]

The Kawasaki JS300 was a popular stand-up jet ski in the late ‘80s. It inherited its JS plarform and features from the JS440 but was powered by a smaller 294cc, oil-injected, single engine. After three short years of production, it was replaced by the more advanced 300SX.

If you want to find out more about this legendary ski, this post is for you.

We at JetDrift have compiled all you need to know into this Kawasaki JS300 review!

1986-1988 Kawasaki JS300 Review

The Kawasaki JS300 was the smallest member of the popular Kawasaki JS stand-up family. Its bigger brothers were the JS400, JS440, and the flagship JS550.

All of these machines were manufactured in Lincoln, NE USA, and shared the first production Kawasaki Jet Ski platform.

This body measured 84 inches in length, 24.4 inches in width, and 25 inches in height and was made of fiberglass-reinforced Sheet Molding Compound (SMC).

While its siblings enjoyed twin power sources, the Kawasaki JS300 was powered by a smaller, single-cylinder engine. This unit was a 2-stroke, 294cc, vertical single Kawasaski marine engine rated at 30 HP.

This engine was engineered with many innovative features, including:

  • 2-stroke, vertical-single, piston reed valve configuration
  • Open-loop water cooling system
  • Mikuni BN34 diaphragm type carburetor (28mm venturi)
  • Oil injection system
  • Magneto CDI ignition
  • Electric start
  • NGK BR7ES spark plug
Surprisingly, the engine was controlled by an ATV-like thumb throttle lever that featured a throttle limiter as well.

There’s no question that the key advantage of this engine was its advanced oil injection system. This made the riders’ lives much easier since they didn’t have to bother with the oil-gas premix anymore.

Thanks to its small single engine, the dry weight of the JS300 was only 222.7 pounds, so 3-4 people were even able to launch it by hand from a truck bed.

Engine power was delivered to an axial-flow, single-stage jet pump housing a 6-vane stator and an aluminum 3-blade impeller. This propulsion system ensured a maximum thrust of 243 pounds and a top speed of 33 mph.

The fuel consumption of the JS300 was 3.2 GPH at full throttle, which translated to a cruising range of 36 miles or a playtime of 1.1 hours. It offered very similar performance to the JS400 and JS440, only the JS550 was slightly faster with more torque.

Like any other Kawasaki Jet Ski built on the original 1973 JS hull, the JS300 was also extremely nimble. Riding it well required a lot of athletic skills, a good sense of balance, and tons of practice.

The JS300 came standard with some advanced features, including:

  • Handlebar-mounted start/stop buttons
  • Starter interlock switch
  • Throttle limiter
  • Thumb throttle
  • Continuous self-activating bilge pump
  • 3.5-gallon fuel tank
  • Engine oil level gauge
  • Fire extinguisher compartment
  • Tool kit
  • Control panel cover
  • Deck mats on the tray and the rails
  • Chin pad
The JS300 was still being designed without a safety lanyard, so its engine didn’t stop automatically when a rider fell off into the water.

Instead, the ski started circling in the water, so the rider had to literally catch it to reboard.

Although Kawasaki marketed the SJ300 until 1988, its more advanced successor, the 300SX debuted in 1987.

Kawasaki JS300 Specs Charts

For your convenience, we’ve compiled the key specs of the 1988 Kawasaki JS300 into these charts:

Kawasaki JS300 Engine Specs

Kawasaki JS300Engine Specs
Engine type2-stroke, vertical single, piston reed valve, water-cooled
Displacement294 cc (17.9 cu in.)
Bore and stroke76.0 x 64.9 mm (2.99 x 2.55 in.)
Compression ratio7.2 : 1
Ignition systemMagneto CDI
Lubrication systemOil injection (break-in period: oil injection and gas/oil mixture 50:1)
CarburetorMikuni BN34 diaphragm type (28 mm venturi)
Starting systemElectric
Battery12 V 19 Ah

Kawasaki JS300 Tuning Specifications

Kawasaki JS300Tuning Specifications
Spark Plug TypeNGK BR7ES, NGK B7ES
Spark Plug Gap0.7 ∼ 0.8 mm (0.028 ∼ 0.032 in.)
Ignition Timing18° BTDC @ 6 000 r/min (rpm) - 1.99 mm (0.078 in) @ 6 000 r/min (rpm)
Carburetor Idle Speed - in water1 700 ±100 r/min (rpm)
Carburetor Idle Speed - out of water2 200 ±100 r/min (rpm)
Compression Pressure1200 kPa (12.0 kg/cm2) (171 psi) - open throttle

Kawasaki JS300 Drive Shaft

Kawasaki JS300Drive Shaft
CouplingDirect drive from engine
Jet Pump TypeAxial flow, single stage
Jet Pump Thrust110 kg (243 lb)
SteeringSteerable nozzle
BrakingWater drag

Kawasaki JS300 Performance

Kawasaki JS300Performance
Maximum Speed53 km/h (33 mph)
Minimum Turning Radius2.75 m (9 ft)
Draft (stationary)200 mm (8 in)
Fuel Consumption12 L/h (3.2 US gal/h) @full throttle
Cruising Range (1)57 km (36 mi) @full throttle
Cruising Range (2)1.1 hrs

Kawasaki JS300 Dimensions

Kawasaki JS300Dimensions
Overall length84 in (2140 mm)
Overall width24.4 in (620 mm)
Overall height25 in (640 mm)
Dry Weight101 kg (222.7 lbs)
Fuel tank capacity3.4 US gal (13 L) including 0.9 (3.5 L)

Kawasaki JS300 Fuel and Oil

Kawasaki JS300Fuel and Oil
Engine Oil Type2-stroke, BIA Certified for Service TC-W
Engine Oil Tank Capacity1.7 L (1.8 qt (US)
Starter Gear Housing Oil - GradeSE or SF class
Starter Gear Housing Oil - ViscositySAE10W40, 10W50, 20W40, or 20W50
Starter Gear Housing Oil - Capacity0.2 L (0.21 US qt)
These charts are for informational purposes only! For exact specifications, please refer to the factory manual.


As a takeaway, we’ve answered the most common questions about the 1986-1988 Kawasaki JS300!

What is a Kawasaki JS300?

The JS300 was a vintage single-cylinder, stand-up Kawasaki Jet Ski.

When did the Kawasaki JS300 Come Out?

The Kawasaki JS300 debuted in 1986.

What Years Did Kawasaki Make the JS300?

Kawasaki marketed the JS300 from 1986 through 1988.

What Size was a Kawasaki JS300?

The Kawasaki JS300 measured 84 inches in length, 24.4 inches in width, and 25 inches in height, while its draft was 8 inches.

How Much Did a Kawasaki JS300 Weigh?

The dry weight of the Kawasaki JS300 was only 222.7 pounds.

How Many People Could Ride on a Kawasaki JS300?

The Kawasaki JS300 could carry only one rider.

What Kind of Engine was in the Kawasaki JS300?

The Kawasaki JS300 was powered by a 2-stroke, 294cc, vertical single Kawasaki marine engine.

Was the Kawasaki JS300 Supercharged?

The Kawasaki JS300 was powered by a naturally-aspirated engine.

Was the Kawasaki JS300 a 2-stroke?

Yes, the Kawasaki JS300 was powered by a 2-stroke engine.

How Much Horsepower Did a Kawasaki JS300 Have?

The Kawasaki JS300 produced 30 HP out of the box.

How Much Oil Did a Kawasaki JS300 Hold?

The Kawasaki JS300 was designed with an oil system featuring a 1.8-quart oil tank.

How Much Fuel Did a Kawasaki JS300 Hold?

The Kawasaki JS300 was equipped with a 3.5-gallon fuel tank.

How Much Fuel Did a Kawasaki JS300 Use?

The claimed fuel consumption of the Kawasaki JS300 was about 3.2 GPH at full throttle.

What was the Fuel Range of the Kawasaki JS300?

The fuel range of the Kawasaki JS300 was about 36 miles (1.1 hours) at full throttle.

How Fast Did a Kawasaki JS300 Go?

The top speed of a Kawasaki JS300 was about 33 mph under ideal conditions.

Did the Kawasaki JS300 Have a Reverse?            

No, the Kawasaki JS300 didn’t have a reverse system.

Did the Kawasaki JS300 Have a Brake?

No, the Kawasaki JS300 was manufactured without a brake system.

How Much Does a Kawasaki JS300 Cost?

The asking price of a used Kawasaki JS300 varies between $1,000 and $3,000 depending on the year and its condition.