Kawasaki pumps up the volume. On the figurative side, the company has given its flagship Ultra even more power. The Jet Ski Ultra 310LX adds 10 horses to the previous model, but the minor jump isn’t about bragging rights. It’s the result of engineers fine-tuning the existing engine for increased durability and efficiency. New is a heat-resistant plastic intake manifold that boosts both low-range and midrange power, cast pistons with a groove pattern designed to improve oil retention, a freer-flowing fuel pump, one more oil jet per piston to keep the engine cooler, a slosh-reducing oil pan, an additional sound-reducing water box, and larger oil return holes in the crankcase. At the pump, the impeller sports a new three-blade design and longer nose, with the promise of increasing acceleration while reducing noise and rattles. Add this laundry list of tweaks to an already-powerful 1,498 cc engine boosted by a supercharger/intercooler combo, and you’ve got a great boat made better. Acceleration during testing proved brutally strong, with a newfound midrange snap en route to the peak speed we achieved of 67 mph.
There’s more buzz. The 310LX is the first production watercraft to feature an original equipment manufacturer (OEM) sound system. Kawasaki’s Jetsounds features a pair of aft-facing, 30-watt waterproof speakers powered by two 20-watt amplifiers. A Jensen-produced head unit is integrated into the oversize handlebar pad. The music’s source is housed within the glove box in a choice of waterproof bag (for iPhones and the like featuring a standard 3.5 mm headphone jack) or waterproof aluminum cylinder (for USB memory sticks). Will sound distract drivers and annoy the neighbors? That was our initial contention, but after using the system we found it added to the ride, much like listening to music in a boat. We also found the volume adequate to hear while underway, yet not so overpowering that it would raise complaints from those on shore. Responsible use is key, but as boats have long featured stereos, we’re willing to give Ultra buyers the benefit of the doubt here.
Of course, below all that power and sound is one of the best big-volume hulls in production. Thanks to its deep, 22.5-degree deadrise, it clove through offshore waves with precision and almost never wavered from its line. In calmer conditions, electric trim allowed us to drop the bow and corner with the agility normally expected of a much-smaller craft.