Compare Specs Discover '24 PWCs Browse Reviews
Hydrospace S4 Specs and Review [Video]

Hydrospace S4 Specs and Review [Video]

The Hydrospace S4 was the first 4-stroke stand-up jet ski in history. This legendary machine was built on a well-designed platform and featured a turbocharged 2-cylinder, 4-stroke, 749cc engine rated at 110 HP. This means, contrary to popular belief, that the Kawasaki SX-R 1500 was not the world’s first stand-up ski!

If you want to find out more about this amazing ski, keep reading. We’ve compiled the specs and all the key info into this Hydrospace S4 review!

Hydrospace S4 Review

The Hydrospace was a boutique jet ski manufacturer established in Pöchlarn, Austria. Despite its small size, the company and its skis quickly became famous and won several World Championships.

The legendary Hydrospace S4 hit the market in September 2005 as the world’s first 4-stroke stand-up PWC.

This ski was powered by a turbocharged 4-stroke, 749cc twin featuring digital electronic map injection, open-loop cooling system, and a dry-sump oil system. Thanks to these advanced features, the Hydrospace S4 pumped out 110 HP at 7500 RPM.

It’s a lesser-known fact that this power source was a modified Weber MPE750 engine provided by Swissauto. This small Swiss-based company specializes in developing and manufacturing internal combustion engines for various purposes.

Swissauto designed several race-winning engines for racing vehicles such as cars, GP motorcycles, and snowmobiles. When Hydrospace contacted the company in the mid-2000s, it had already retired from powersport racing, but this new challenge caught their interest.

In collaboration with Hydrospace, Swissauto developed the world’s first 4-stroke stand-up jet ski engine. And they did a really good job!

The all-new Hydrospace S4 debuted in the 2005 European Championship at Wörthersee, ensuring its qualification for the oncoming World Championship Finals.

In this Arizona competition, the Hydrospace S4 competed in four different categories and won World Champion titles in three of them! This was very surprising as the competing machines were proven Yamaha and Kawasaki stand-up skis.

The Hydrospace virtually won every Word Finals it participated in in the following years, translating to 17 World Champion victories in only three short years.

This amazing success was thanks to the high-performance turbocharged engine, as well as the carefully-designed fiberglass racing hull.

Regarding dimensions, the Hydrospace S4 measured 90 inches in length, 29 inches in width, and 30 inches in height. The ski was equipped with a 4.8-gallon fuel tank and weighed only 370 pounds.


The main rival of Hydrospace PWCs was the Kawasaki SX-R 800, as these skis were nearly the same size. The dry weight of the SX-R was 20 pounds less, and it utilized a 781cc, 80 HP engine. But the key advantage of this ski was arguably its moderate price ($5,999), which was roughly half the price of the S4.

Another stand-up ski of this era was the bulky Sea-Doo 3D, which had a dry weight of 565 pounds (in stand-up configuration). As you can imagine, this wasn’t the most popular stand-up ski ever built.

When it comes to modern 4-stroke stand-ups, the dry weight of the smaller Yamaha Superjet is 375 pounds, while the Kawasaki SX-R 1500 weighs 503 pounds.

At first glance, the S4 was very similar to the 2-stroke SX-R 800, but the custom top deck and different weight distribution offered quite different handling.

Combining the lightweight hull with the relatively heavy 4-stroke engine moved the center of gravity towards the bow. But contrary to expectations, the ski wasn’t nose-heavy.

Instead, it was a well-balanced machine with a ton of potential.

It provided excellent stability at even higher speeds, and in the turns it handled like a dream. The top speed of the Hydrospace S4 was about 55 mph in stock condition when its stainless-steel exhaust loudly roared in a deep-sounding tone.

Its advanced scoop grate offered an outstanding hook up, so porpoising was never an issue on a Hydrospace.

The only drawback of this engine was arguably a little turbo la, which the rider had to get used to.

The special “hull-deck flanges” integrated into each side of the body and worked like widened sponsons. These flanges aggressively cut into the water, ensuring sharp turns and allowing the rider to use a lot of body English.

Many riders claimed that this ski didn’t compare to any other PWC in its time. Therefore, the ski instantly became popular among racers and hardcore recreational riders as well.

Standard features included an adjustable aluminum handle pole, finger trigger, carbon fiber handlebars, and cambered footwell mat.

In 2007 Hydrospace was acquired by the Italian Benelli, and the ski was rebranded as Benelli-HSR. Until 2008 the new manufacturer only offered the HSR-Benelli S4 stand-up. Later the company was rebranded again as “Benelli.”Due to these frequent changes, the Hydrospace S4 was known for various names such as:

  • Hydrospace S4 110
  • Hydrospace S4
  • Benelli Hydrospace S4
  • HSR-Benelli S4 110
In 2008 Benelli revealed its “new” lineup featuring four different stand-up skis, including:
  • HSR-Benelli S4 110 (former Hydrospace S4)
  • HSR-Benelli S4 Pro Edition (former Hydrospace S4)
  • HSR-Benelli Series-S Pro Edition
  • HSR-Benelli Series-S Race Edition
As the name suggests, the base S4 and the S4 Pro Edition were still based on the original Hydrospace S4, while the Series-S were new stand-up models in the lineup.

The S4 remained part of the fleet until 2012, when it was discontinued to make room for the new Benelli B3R. To the greatest regret of many fans, this new model was already powered by a Benelli engine and proved to be far less reliable than its predecessor.Therefore, the Benelli B3S never became commercially successful and disappeared from the market within a couple of years.

Despite this, the company still exists, and after a new rebranding, it has a runabout PWC under the brand name of Belassi Burrasca.

Hydrospace S4 Specs Chart

For your convenience, we’ve listed the Hydrospace S4 specifications in these charts!

Hydrospace S4 Dimension Chart

Hydrospace S4Dimensions
Length229 cm (30 in)
Width74 cm (29 in)
Height75 cm (30 in)
Dry weight168 kg (370 lbs)
Recommended maximum loading120 kg (265 lbs) (including skipper, fuel weight and items for personal use)
Hull materialFibreglass

Hydrospace S4 Engine Specs Chart

Hydrospace S4Engine Specs
Type2 Cylinder parallel twin with balancershaft
Displacement749 cm3
Engine stroke4-stroke
Bore85 mm
Stroke66 mm
Power Output81 KW (110 HP) SAE 1228/7500 1/min
Max. Continous RPM8500-9000 1/min regulated through E.C.U.
SilencerStainless steel single-pipe exhaust system
Mixture preparationElectronic petrol injection

Hydrospace S4 Fuel and Oil Specs

Hydrospace S4Fuel and Oil
Oil fill volume3,3 - 3,5l
oil change with filter3,7 - 4,1l
refilling3,7 - 4,1l
Oil SpecificationHydrospace 10W-60 Full synthetic, API SJ-CF, ACEA A3/B3
Fuel content18 litres (4.8 gal)
FuelUnleaded fuel DIN 51607 between 95 snd 98 ROZ US premium Unleaded fuel (91/92/93 Octane) or 95/98 ROZ ISO 5146

Hydrospace S4 Electrical Features

Hydrospace S4Electrical Features
StarterElectric starting
Voltage supply12 Volts
Battery12 V/18 AH
Working temperature range0° to 48° C
Ignition TypeDigital electronic map ignition, Walbro ECUC-2
Spark Plug TypeChampion RC7PYCB
Electrode gap0,69 – 0,84 mm

Hydrospace S4 Operating Conditions

Hydrospace S4Operating Conditions
Environment- Temperatures0°C – + 45°C
Environment - Height0 – 2000m
Engine compartment temperaturemax. 65°C
Oil temperaturemax. 110°C continuous in oil tank -max. 115°C short time
Thermostat opening point70°C
Tank temperaturemax. 55°C
Fuel pressureturbo engine 3.8 bar
Exhaust back pressuremax. 150 mbar
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 Yamaha Hydrospace S4 700!

What is the Hydrospace?

The Hydrospace S4 was a unique stand-up jet ski primarily built for racing purposes. The ski was released in September 2005 and won 17 World Finals in the following three years!

What Year Was the Hydrospace S4 Manufactured?

The Hydrospace S4 made its debut in 2005 and was marketed through 2007 under the same brand name. By 2008 the model was rebranded as HSR-Benelli S4 and was available until 2012.

Was the Hydrospace S4 a 4-Stroke Ski?

Yes, the Hydrospace S4 was the world’s first production 4-stroke stand-up jet ski.

Where Were Hydrospace Jet Skis Made?

The original Hydrospace S4 was manufactured in Pöchlarn, Austria.

What Was the Hydrospace S4 Made of?

The body of the Hydrospace S4 was made of high-stability infused composite fiberglass, but the ski featured some carbon fiber parts like the handlebars.

What Kind of Engine Did the Hydrospace S4 Have?

The power source of the Hydrospace S4 was a Weber MPE750 engine provided by Swissauto. For the best performance, this 4-stroke, 749cc parallel twin was boosted with a turbocharger.

How Many People Could Ride a Hydrospace S4?

The tiny Hydrospace S4 700 was rated for only one rider and with good reason. Riding with a passenger on this ski was virtually impossible!

What Size was the Hydrospace S4?

The Yamaha Hydrospace S4 700 was 90 inches long, 29 inches wide, and 30 inches high.

How Much Did a Hydrospace S4 Weigh?

The dry weight of the Yamaha Hydrospace S4 700 was only 370 pounds (168 kg).

How Much Horsepower Did a Hydrospace S4 Have?

The Hydrospace S4 700 provided 110 HP at 7,500 RPM.

Was the Hydrospace S4 Turbocharged?

Yes, the Hydrospace S4 was equipped with a turbocharger.

How Fast Did a Hydrospace S4 Go?

The top speed of a Hydrospace S4 was 55 mph under ideal conditions.

How Much is a Hydrospace S4 Worth?

It’s hard to tell the exact price of a Hydrospace S4, as it strongly depends on its year, condition, and location. But as a rule of thumb, the prices typically range from $2,000 up to $7,000.

Is it Worth Buying a Hydrospace S4?

Let’s face it, buying an aged Hydrospace S4 is not the best deal. Parts for this ski are very expensive and hard to find. Therefore, fixing or even rebuilding the ski is often hard to impossible. If you’ve fallen in love with this machine, you should consider an engine swap as this ski runs well even with a less powerful 2-stroke engine.

If you are stuck on 4-stroke stand-ups, you also can’t go wrong with a new Superjet or a Kawasaki SX-R 1500.