Riva Motorsports’ new MR1 Supercharger for the Yamaha FX line of four-stoke watercraft was recently awarded the Aftermarket Product of the Year from Watercraft World magazine. According to the editorial staff of WW, the Riva supercharger was selected not only because it was the first true aftermarket product intended for a four-stroke, but also the fact that the product has provided impressive results in the early stages of its release. The “big picture” behind the product, that being the fact that a successful four-stroke product may just breathe new life into an aftermarket struggling through the waning days of conventional two-stroke technology, was also singled out by Watercraft World.
Riva’s award-winning system includes a bolt-on Vortech centrifugal supercharger, a water-cooled intercooler, and an aluminum air box. The overall boost in pressure is between 4-5 pounds. Coupled with an increase in fuel delivery, the system produces approximately a 30-percent increase in power over stock, according to Riva.
In the development of the supercharger system, Riva tuners Tim Judge and Bruce Clarkson set out to increase the MR1 horsepower from 140 to a range of 175–185 hp. They have documented 189.5 hp at 10,000 rpm. In the 160-horse MR1 High Output engine, Riva targeted a horsepower range of 195-200, and they documented 206 hp at 10,100 rpm. The real numbers — the top speeds — indicate that Riva has recognized about a 10-mph increase in both the FX140 and the FX H.O. Top speeds should realistically peak in the neighborhood of 68-71 mph. Riva also promises a “ton” of bottom-end acceleration gain.
“I wanted to jump in with both feet into the four-stroke performance market,” said Riva Racing owner Dave Bamdas. “It was a big commitment, but it was an investment in the future because we plan to produce parts for four-stroke watercraft of all makes and models. We needed to do it to make a statement to the watercraft community to show that Riva’s in it for the long haul, and that we’re serious about four stroke technology.”
Impressive as it may be, the Riva system doesn’t come cheap. At $4,850, it offers all the engine parts but not the complementing pump parts such as a new impeller ($241) which is almost mandatory, an intake grate ($130), a ride plate ($170), and a sponson kit ($200).
According to Bamdas, the experience of building this product was a great one for his staff. And the knowledge gained from it, he said, has already begun to roll over into other four stroke products. “I kind of took the mentality of racing that we’re going to go out there and show the world what we can do,” Bamdas said. “That’s basically what racing is all about. You prepare for months, make your best stuff, put it on the line, and show them what you can do.” psb
Copyright 2004 Powersports Business