If it’s got an engine in it, I’m interested. If it’s got a ridiculous amount of horsepower, I’m more than interested – I’m riveted. When I heard that Kawasaki’s latest Jet Skis, the Ultra 310LX and Ultra 310R, could pump out over 300 hp, I knew I had to catch a ride – even though I’d never ridden a jet ski or other similar watercraft before in my life.
Kawasaki has been building jet skis since 1973, and they’re the leader in the water. Jet Ski is a brand name, but it has been so successful that the name “Jet Ski” has become the defining term for the whole class of waterjet-propelled personal watercraft, much as “Kleenex” has been adopted for facial tissue and “Google” for doing a web search. Several other manufacturers build their own personal watercraft, including Sea-Doo, Honda, Yamaha and Polaris – only Kawasaki builds the Jet Ski.
Kawasaki’s reputation as a motorcycle manufacturer rests in great part on its intense commitment to racing, and the same is true of its personal watercraft. The past three years have brought numerous championships to the banner. Knowledge and experience gained from competition has been exerted on the new Jet Skis, and it shows.
There’s also a lot of engineering crossover from the motorcycle side of the business to the jet ski side. Specifically, the Ultra 310’s engine is based in large part on the Kawasaki ZX-14 sportbike engine, one of the most potent powerplants on the market. The engine is a liquid-cooled inline four-cylinder design that displaces 1,498 cc. Sportbike demands are very different from watercraft demands, however, so the engine gets a substantially different treatment for the jet ski implementation.
The biggest difference right off the bat is that the Ultra 310’s engine is supercharged, while the ZX-14’s is naturally aspirated (no supercharger or turbocharger applied). A supercharger is a mechanically driven pump that increases the air pressure in an engine’s combustion chamber, which allows the engine to extract more power from its fuel. It’s similar to a turbocharger in intent, but a turbocharger is driven by exhaust gases, and needs time to spool up before its effect hits. There are advantages and disadvantages with each device. Turbochargers have less of a negative effect on fuel economy; but superchargers don’t suffer from the spooling up time (called “turbo lag”), and deliver their effect almost instantaneously, and in a very linear and predictable fashion. That’s what Kawasaki engineers craved for the Jet Ski – power down low, right away. And they got it, 310 hp worth – more than double the output achieved by the non-supercharged, non-turbo ZX-14 engine.
Even though they share a lot in common, a personal watercraft is not a motorcycle, and the demands of scooting across the water are very different from the basics of riding on solid ground. Water produces much greater drag and resistance than tires rolling along pavement, so hull design becomes very important. Designers have to strike a balance between lowering resistance and maintaining stability in the water.
Also, it should go without saying that jet skis have no brakes and no suspension – it should go without saying, but I’m saying anyway, because I didn’t realize it until it was time to ride. Jet Skis also have no rudder or any means of changing direction other than redirecting the jet flow under the water. So, the Jet Ski only turns when it is under power. Cut the throttle, and the craft drifts in the direction it was going already.
The controls on the Ultra 310 are very straightforward. A trigger throttle is attached to the right handlebar – not a motorcycle-style twist grip, for reasons that became obvious to me later. Also on the right side are controls for the cruise control. Yes, cruise control, which is very handy, especially in “No Wake” zones. One touch of the “SET” button, and the Jet Ski puts along at a steady 5 mph, the accepted speed in most harbors.
The left handlebar houses the start and stop buttons. A kill switch is attached to a tether, which was attached to my wrist and ready to cut the power if I fell off.
I climbed on board the Jet Ski, and I was pleasantly surprised at how stable the platform felt. I didn’t have to expend any energy or attention to keeping it from tipping from side to side or front to back. I inserted the yellow “SLO” key into the ignition and brought the ski to life. I thumbed the start button, and the Jet Ski began to creep forward.
A lever on the left side of the steering column can be positioned from “F” to “R” (“Forward” to “Reverse”), and there’s a way of finding a neutral, but its way to fussy to bother. If you’re going to sit still on a Jet Ski, just shut down the engine.
Pulling away from the dock, it’s important to keep the speed low and to avoid creating a wake that might disturb the boats that are tied up in the harbor. Kawasaki helps make this easy with a “Set” button that causes the Jet Ski to maintain a steady cruise of 5 miles per hour, the usual “No Wake” speed limit.
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