Gallery: RIVA Racing’s 2018 Sea-Doo RXT-X 350

For the last few years, RIVA Racing has offered a specialty-built, Limited Edition high-horsepower, top-of-the-line performance racecraft (built in production runs of 25). This is not one of them. Rather, the 2018 RIVA Racing Sea-Doo RXT-X 350 is a true 350-horsepower machine that you can build yourself using the list of parts that RIVA Racing will have ready for simultaneous release (this coming January) as the new 2018 Sea-Doo RXT-X 300 you saw revealed on The Watercraft Journal last week.

Based upon the new for 2018 ST³ hull, the supercharged and intercooled RXT-X 300 already promises to be a worthy successor to the outgoing T-X. Sure the newcomer is wider (from 48.2-inches to 49.4-inches) than its predecessor, but it’s surprisingly shorter (139.2-inches to 135.9-inches). More importantly, the ST³-based RXT-X 300 is also substantially lighter (828-pounds from ‎914-pounds).

Less weight, added stability, better rough water handling and Sea-Doo’s new Launch Control (a iTC feature that automatically adjusts pump angle for optimal acceleration), all adds up to a veritable monster for racing and/or friendly competition. Given the opportunity to familiarize themselves with the ’18 RXT-X 300 well before the public reveal, the team at RIVA Racing spent a few days testing. “I thought it was great. It’s very well balanced – static or at speed,” recounted RIVA President Dave Bamdas.

With much of the powertrain direct carry-overs from the previous generation RXT-X 300, a large portion of the performance products already tested and developed by RIVA remained applicable.

For their one-of-one RXT-X 350, RIVA managed to push the Sea-Doo’s stock top speed of 68mph at 7,500rpm to a blistering 85mph at 8,500rpm (and that was conducted with 1/3 tank of fuel, trim set at neutral, sea level elevation, air temp 80-degrees F, states RIVA).

“Like the Spark,” Bamdas added, “The new RXT-X 300 has OEM sensors fixed in the air box. In designing a new RIVA Sea-Doo 2018 RXT/GTX 300 Power Filter (PT# RS13120), we developed a really nice stainless steel bracket that relocates those sensors.” The 350 build employed a RIVA MaptunerX BRP Bundle (All except SPARK) (PT# RS110SC-B) to reflash the ECU, a RIVA Sea-Doo 2018 RXT/GTX Catch Can/Engine Breather Kit (PT# RS19050-BCC-2), and a RIVA Sea-Doo RXP/RXT 300 GEN-4 Power Cooler (PT# RS1753-PC-I).

Bamdas noted, “For the new RIVA Sea-Doo 2018 RXT/GTX 300 Intercooler Tubing Upgrade Kit (PT# RS17120-TK), we went with these new blue silicone intercooler tubes. They’re lighter, easier to keep clean and look really cool.” The rest of the engine build included a RIVA Sea-Doo Pro-Series TiAL Blow-off Valve Kit (PT# 002573), a RIVA Sea-Doo 230/300 Open Loop Cooling Kit (PT# RS1013-140), the RIVA Sea-Doo 230/300 Intake Manifold Upgrade Kit (PT# RS12140-IMUK), RIVA Sea-Doo 300 XX Charger (PT# RS17140-135), RIVA Sea-Doo Rising Rate Fuel Pressure Regulator Kit – `08 & Newer (PT# RS12050-RRFPR-08), Bosch VT1100 Fuel Injector Kit (PT# VT1100-INJK) and RIVA Valve Train Upgrade Kit – Seadoo 4TEC (RS19050-VTU).

Developing a new exhaust system proved slightly tricky. Bamdas illustrated, “If you look closely at the hull, you’d see a pronounced step at the rear. We couldn’t drill a hole for our regular round exhaust outlet, so we had to come up with something different.” What RIVA created was a rectangular port specially CNC-machined for the new RIVA Sea-Doo RXT-X 300 Rear Exhaust Kit (PT# RS15120) that is fed by a RIVA Water Box RXP/RXT 300 (PT# RS16141). Explaining further, Bamdas emphasized, “Once you remove the plate (engine cover), there’s a lot of access to the engine compartment. It’s really nice.”

Handling is sharpened by a RIVA Sea-Doo 2018 RXT/GTX 300 Top-Loader Intake Grate (PT# RS22120), a RIVA/Solas Race Pump & Nozzle (PT# SRZ-PM-159/83), a new Skat-Trak 3-Blade Swirl Impeller 15/19 (PT# SS618328SW15/19), RIVA Sea-Doo 2018 RXT 300 Fixed Performance Trim Tab Kit (PT# RS27120-FPT) and prototype RIVA Sea-Doo 2018 RXT/GTX Pro-Series Sponsons (PT# RS26120) featuring a stepped-and-compound curved design similar to those offered for the GP1800.

Above the folding deck, RIVA had to redesign its RIVA Sea-Doo 2018 RXT-X Pro-Series Steering System (PT# RS20120-B) to accommodate the new touch pads that replaced the previous toggle switches. The steering system is also paired with RIVA PRO-BAR 32” Runabout Bars (PT# RY204) and ODI Rogue Lock-On Grips, 120mm, With Flange (PT# L30RGB-S). Providing the final touches were new 2018 Sea-Doo RXT-X 350 Custom Build Traction Mats (PT# RS5-HTRM-120) and a hand-stitched 2018 Sea-Doo RXT-X 350 Seat Cover. Exotic Signs provided the unique, one-off graphics as well.

Again, while the package cannot be sold to you as a finished ski, RIVA Racing will have everything shown here, and anodized (where applicable) at by the New Year. While these images are great to drool over, the 2018 RIVA Racing Sea-Doo RXT-X 350 will also be on display next week at the RIVA Racing booth at the 2017 Blowsion IJSBA World Finals in Lake Havasu City, Arizona, if you’d like to paw over it in person.

RIVA_2018_RXT-X 300_Custom_Build_Side_View RIVA_Seadoo_RXT-X_300_Rear_Traction RIVA_Seadoo_RXT-X_300_Steering RIVA_Seadoo_RXT-X_300_Graphics RIVA_Seadoo_RXT-X_300_Engine_ThreeQuarter RIVA_Seadoo_RXT-X_300_Rear_Exhaust RIVA_Seadoo_RXT-X_300_Engine_TopView RIVA_Seadoo_RXT-X_300_Seat_Cover_03 RIVA_Seadoo_RXT-X_300_Seat_Cover_02 RIVA_Seadoo_RXT-X_300_Seat_Cover RIVA_Seadoo_RXT-X_300_Top_View RIVA_2018_RXT-X 300_Custom_Build_Side_View_White_Background

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Kevin Shaw

Kevin Shaw

Editor-in-Chief – Kevin Shaw is a decade-long powersports and automotive journalist whose love for things that go too fast has led him to launching The Watercraft Journal. Almost always found with stained hands and dirt under his fingernails, Kevin has an eye for the technical while keeping a eye out for beautiful photography and a great story.


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  1. Avatar
    derek 15 March, 2018 at 21:37 Reply

    This article is not true. I put the 15/19 on mine and lost 7 mph. from 77 to 70. And ran to many rpm’s….. Riva has, since then, had skat trak repitch to /21. Please be more accurate. I call BS!!!!

    • Kevin Shaw
      Kevin Shaw 15 March, 2018 at 21:59 Reply

      Did you also install all of the other parts, and reflash the ECU with the MaptunerX software or just install the prop? Obviously, things work in conjunction with the XXX Supercharger, tuner and reflash. We’ve ridden RIVA’s StageIII kit for the ’18 RXT-X 300, and yes, it works – but as a package.

      • Avatar
        derek 15 March, 2018 at 22:46 Reply

        Put more horse power on an under pitched impeller…. let me know how that works out…. and yes… I have a re-flash and a race pump and a free flow exhaust and an imuk…. This article only calls for the XX charger….. not the XXX…. as does the riva 350…. Anyway… on the date of your article the intake wasn’t made yet….

  2. Avatar
    derek 15 March, 2018 at 22:50 Reply

    Not troll….. just a dude trying to read an article from someone who said they “know” and spending money….. your article quotes people saying they tested it…..

  3. Avatar
    derek 15 March, 2018 at 22:56 Reply

    I love this bike, and cant say enough good stuff about RIVA. They are awesome. Best service EVER. Best people and VERY knowledgeable. I’m not a troll. I’m just sayin’..

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