I found myself laughing. In fact, I was laughing a lot. Unlike test riding the ludicrously fast (88mph!) RIVA-tuned GP1800 a few minutes earlier – which is serious business because one misstep at those speeds could result in an unexpected trip to the hospital – the lightly reworked Yamaha EX WaveRunner equipped with RIVA Racing’s Stage 1 Kit was pure, unrefined joy and it was showing on my face. The combination of an ECU tune, a new prop and a bit of breathing assistance for the EX TR-1 engine was all it took to turn Yamaha’s happy-but-ultimately-humdrum Rec Lite entry into a lively, alert and rowdy little colt.

When first introduced to the all-new EX WaveRunners, I found them to be a very conservative response to Sea-Doo’s Spark, which is actually very much in line with Yamaha’s modus operandi. The EX is well-built, solid and well-balanced (all fancy euphemisms for being 170-pounds heavier than the Spark). Yet, that added weight serves a valid purpose; gone is the loose, tipsy feeling, replaced with a hull that feels well-seated and predictable. The bench narrows at the knee allowing for comfortable-yet-forward seating, as the EX, EX Sport and EX Deluxe are meant to carry a trio of riders, offer more storage and are significantly more stable.

Powered by a 100-horsepower TR-1, the EX-edition powerplant is slightly restricted for the Rec Lite unit by a revised exhaust manifold, muffler and redesigned shaft coupler driving the completely original two-piece pump and venturi. The 3-cylinder, four-stroke is seated beneath the one-piece seat and a large black plastic base. The base comes off quickly with basic hand tools and requires no hoist or extra set of hands to heave out of the way. Already tuners have found that the VX-level TR-1, producing a base 120-horsepower, responds brilliantly to modifications, leading all to believe the EX to be equally responsive. RIVA chose to prove that fact this day.

The RIVA Racing Stage 1 Kit for the Yamaha EX is constituted of four parts: the RIVA MaptunerX Yamaha TR-1 Bundle, RIVA Yamaha EX Power Filter Kit, RIVA Yamaha EX Free Flow Exhaust Kit and a Solas Yamaha Concord 144mm 12/17 Impeller. It doesn’t sound like much, but the package alone adds a solid 5 miles per hour to the unit’s top speed (56mph @ 8,400rpm over the stock 51mph @ 7,500rpm) and a significant jump in the EX’s 0-to-50 acceleration, leaping to speed in 7.2 seconds over the previous 10.5 seconds. The throttle’s immediacy is palpable and the increased response plays a big part in the EX’s newfound playfulness and ability to pull itself out of a hard turn.

In RIVA’s own words, the “Maptuner X programmer is utilized to reflash your original ECU (Engine Control Unit) for added performance. The MaptunerX Bundle delivers instant plug-in horsepower! Quickly and easily load our Stage 1 performance tune into your Yamaha ECU eliminating the need to ship out your ECU for programming. The MaptunerX features a slick, full color, touch screen display for easy operation. Includes full access to RIVA’s World Famous Tuning Library along with unmatched technical support. Easily switch between performance tunes and then back to stock settings if you wish.”

The RIVA EX Performance Power Filter replaces often restrictive factory intake opening up the engine’s intake to cool, dense air, improving both throttle response and top speed; as the RIVA EX Free Flow Exhaust Kit replaces the choking factory sound suppression system (between water box and hull exit) helping relieve backpressure and lower engine operating temperatures. Finally, the new Solas impeller features a new design specific to the EX and “incorporates a large blade area and superior hub design that deliver increased acceleration and top speed”, according to RIVA.

I got to spend as much time on the Stage 1-equipped EX as I wished and admittedly found myself taking it out not once, or even twice but three separate times. In fact, during the test session, 8 different riders took the EX out on the lake and experienced the same joy as I did, nary once requiring a refill of its 13.2-gallon fuel tank. Two thirds of RIVA’s Research & Development team were on-hand for questions, and both Bruce Clarkson and Jesus Garcia said that a ride plate, sponsons and intake grate were soon coming, but that as it stood, the Stage 1-equipped EX was using all stock handling products – and it showed.

Putting the EX on its bond rail and power sliding it like Rhys Millen is effortless. In fact, pinning the throttle uproots the EX and will jut skyward when weighted on the stern. (Jokes of “Yamaha’s new ‘TRIXX EXX” earned some solid laughter.) While somewhat nimble, the stock EX simply didn’t pack the responsiveness of a Spark in “Sport” mode until now. Racy turns, winding Figure 8’s, and the aforementioned power slides kept many of us entertained until exhaustion. Suddenly, one tester noted, putting an EX on a closed course against the Sparks sounded like a good idea. With current IJSBA rules notwithstanding, the RIVA Racing Stage 1 kit for the EX WaveRunner retails for $1,659.35.

By : KEVIN SHAW | 2017