By Cody Hooper
Privateer Motorsports and Assault Industries turned a Yamaha YXZ1000R into a turbocharged, rear-wheel-drive desert race car with a solid rear axle. When we met the team in Barstow in 2018, the car combined a 125-inch wheelbase, 80-inch width, 21 inches of front travel and 24 inches of rear travel with a claimed 350 crank horsepower. It was a radical answer to a practical racing problem: repeated failures of the original rear CV joints and axles.
This is a look at a custom race car as built and tested in 2018. Its specifications and the parts fitted to it describe that build, not currently available Assault Industries products or a production conversion kit.
Why a solid rear axle?
Ricky Veinot of Privateer Motorsports and Assault Industries had previously built two turbocharged YXZ1000R vehicles. As power and speed increased, the rear CVs and axles became a durability concern. Their response was a purpose-built tube chassis with a triangulated four-link rear suspension and Toyota 8-inch solid axle. The car retained the stock-location front suspension pivots to meet the racing class rules the builders were targeting.
The fixed-width rear axle eliminates the CV articulation and changes in rear track width associated with the original independent suspension. Privateer and chassis fabricator Jason Montes developed the rear layout, while Assault contributed engineering and modeling resources. This is a one-off race-car solution with a substantial chassis redesign, rather than a bolt-on upgrade for a trail YXZ.
Chassis and suspension
The Privateer-built chassis stretches the YXZ to a 125-inch wheelbase and measures 80 inches wide. Up front, custom arms and shock towers support 21 inches of strapped wheel travel. The rear four-link cycles through 24 inches. Each corner uses a King coilover and bypass shock, with 2.5-inch units in front and 3.0-inch units at the rear. The front shocks attach to the lower arms to achieve the intended angle and motion ratio.
Turbocharged three-cylinder and geared drivetrain
Privateer built the Yamaha three-cylinder with custom CP pistons, Carrillo rods, ported head, Daniel Crower cams, upgraded valvetrain and a custom turbo system. The original build specification lists a Comp 2.0 5353 oilless turbocharger, Burns collector, titanium exhaust tubing, custom intercooler and oversized CBR radiator. Its reported output was 350 horsepower at the crank on race fuel; that is a build claim, not a wheel-dynamometer measurement.
The geared YXZ transmission received cryogenic treatment and micro-polishing, Barnett clutch components, a Tube Works clutch oil modification and a separate cooler. A MoTeC ECU configured by John Reed Racing provides launch control and adjustable boost. The drivetrain sends power only to the rear wheels through a custom driveshaft and Toyota 8-inch axle with a spool and chromoly shafts.
Inside the race car
A widened cockpit houses Sparco race seats, Assault Industries five-point harnesses, a billet short-throw shifter and convex mirrors. The aluminum dashboard carries an AEM CD7 display and Switch Pros controls. Rugged Radios communications and a MAC 4.2 fresh-air system equip the crew, while KC lighting supports night racing and repairs. The team quoted a ready-to-race weight of 2,127 pounds with fluids, spare tire, tools and parts aboard.
Our Barstow ride
In our short 2018 Barstow test, the car stayed composed through big whoops and G-outs, with the solid rear axle tracking straight under power. The turbo three-cylinder delivered a distinctive exhaust note and strong acceleration. The wider cabin gave its occupants more room, and removing the rear-mounted spare opened access to the powertrain. We experienced no mechanical interruption during the session, though contact with a rock bent a rear brake rotor and caused a squeal.
Build highlights
- Privateer Motorsports tube chassis: 125-inch wheelbase and 80-inch width
- Custom front suspension: 21 inches of travel; King 2.5-inch coilover and bypass shocks
- Triangulated four-link rear suspension: 24 inches of travel; King 3.0-inch coilover and bypass shocks
- Toyota 8-inch solid axle with spool and chromoly axle shafts; rear-wheel drive
- Privateer-built turbo Yamaha three-cylinder; claimed 350 crank horsepower on race fuel
- MoTeC engine management; upgraded clutch and transmission cooling
- KMC beadlock wheels and 32-inch EFX Moto Hammer tires
- Sparco seats, Assault harnesses and shifter, Rugged Radios communications and KC lights
The YXZ1000R left the U.S. new-model lineup after 2025, but builds like this remain a striking part of its racing history. For the stock platform and its evolution, see our Yamaha YXZ1000R history and model guide. Assault still maintains a YXZ parts collection; check individual listings for present fitment and availability. The original article’s photo gallery can remain below this text in WordPress.
