Jason Weller left GM and started Weller Racing in 2006, and his quad racing and STEM backgrounds led him to specialize in building race engines for ATVs and later UTVs. By 2008, Weller Racing was making waves in CORR, with wife Corry at the wheel of WR Rhinos. That led Jason, twin Jeff, and Corry to start the SR1 project, which involved stuffing an R1 Yamaha road-race engine into a modified Rhino chassis to create a 2WD UTV spec-racing class. The Wellers worked with the Lucas Oil Off-Road Racing Series (LOORRS) to create the SR1 Rhino class starting in 2010, so it was natural that Great American Short-course (GAS) continued the partnership. Jason and Dustin Nelson traded wins and top-qualifier points at the first two GAS SR1 rounds, but Jason dominated the third and fourth rounds, while Dustin didn’t attend, so Jason has a huge points lead. We got a chance to check out Jason Weller’s SR1 1000 at the first two rounds. The next-generation SR1 has new fenders based on the Yamaha Wolverine, new shock mounts, and a laser-cut engine enclosure.

Jason Weller’s SR1 1000 took the top qualifier and main wins at Round 2 of the Great American Short-course series, and he was second behind Dustin Nelson at the first round, so he sat tied for the lead going into the Glen Helen Raceway double-header.


Weller SR1s can be bought as a complete roller chassis, or racers can build their own SR1s with numerous WR kits and upgrades. The $19,288.95 SR1 roller chassis includes a racing frame, which is basically a widened Rhino with 4 inches more wheelbase, LSR A-arms built to WR spec, Fox Factory 2.5 Podium RC2 shocks, heavy-duty front spindles with 7/8-inch Uniballs and tapered bearings, a front-steer rack with built-in quickener, tie-rods, front rotors with Wilwood calipers, Raceline 12-inch beadlock wheels, 26-inch Maxxis Ceros tires, an SR1 ready engine mount kit for 2004–2008 R1 engines, 12/52 sprockets, a 530 chain, CV joints and boots, 300M axles, a big rear-brake kit with a Wilwood caliper, adjustable rear torsion-bar kit, and a TIG-welded chromoly cage.


Jason Weller’s SR1 1000 has the spec Yamaha R1 engine completely enclosed by bodywork, and this is a good look at the mounting kit, big brake and exhaust headers. The plate in front of the R1 motor holds the SR1 hand-shift.

The widened frame and longer A-arms give the SR1 a 76-inch width, 14.25 inches of front travel and 15.5 inches of rear travel. The LSR +6.5-inch A-arms have adjustable caster and camber. Spec-class R1 engines are sealed; only intake, exhaust and ECU tuning can be modified. Weller makes a custom four-into-one header with a 2.5-inch collector, and customers can choose their own muffler, usually Magnaflow. With a K&N air filter and WR-tuned Dynojet R1 Power Commander 5 ($265), SR1s make 180 crank horsepower and 140 rear-wheel horsepower! A WR YXZ1000R tops out at 81 mph, and an SR1 can easily double that.

Weller’s SR1 complete mount and drive kit with big brakes is $4300 and includes the complete R1 engine mounts, bolts and spacers, carrier frame, inner carrier with bearings and seals, inner drive hub kit, big brake rotor with Wilwood caliper, 300M axles, inner CVs, axle clips, 12T/52T sprockets, an 86-link 530 chain, rear outer hubs with a Rhino lug pattern, and all hardware to mount a 2004–2008 R1 engine, which can be found on eBay for $600 to $800. Options include Summers Brothers axles (+$100) and a rear hub bushing kit (+$249.99).

The high-performance race radiator is $650 with a six-port-design CBR radiator with large Spal fan. Jason fabricated the mount and roost screen and added a large coolant overflow reservoir.

Weller’s SR1 shifter kit ($306.78) mounts to the engine mount, and the chromoly linkage is a short-shift design for crisp sequential shifts. Jason runs a hydraulic clutch on the shifter that pivots on the engine cover next to the steering wheel. Weller also gives racers the option of a left-foot clutch pedal. Weller’s high-performance race radiator (CBR, $650) has a large fin design for more airflow and less packing with roost, a six-port design for the R1 engine, and a high-performance Spal fan. The core is 22.25 inches wide by 13.75 inches tall by 3.0 inches thick, and weighs 15.1 pounds with universal mounts. Jason fabricated triangular mounts welded to the frame with a wire-mesh screen and large coolant reservoir attached to one side.

The cockpit has a Sparco wheel with a DFR hub, a hydraulic clutch on the sequential hand-shifter, a Wilwood brake-bias adjuster, battery disconnect switch and Aim MXS Strada digital gauge package with GPS, lap times, shift-point alarms and much more.


Weller sells the Sparco Pro 2020 QRT racing seat for $745; it’s designed for a medium-sized driver with a waist size up to 34 inches and is Sparco’s deepest-bolstered seat. It’s FIA approved and has a lightweight QRT fiberglass shell and fire-retardant, non-slip fabric. It also has removable and adjustable lumbar cushions and seat bottom. The seat mount is $90. Shoulder harness openings are raised over the original 2000 QRT, and Jason uses a DragonFire four-point auto-latch harness ($109.99) and a Sparco steering wheel with DFR quick-release hub. His SR1 also has an electronic power steering unit.

Lone Star Racing builds the +6.5-inch A-arms to Weller specs, and the Fox Factory Podium 2.5 RC2 piggyback shocks have high- and low-speed compression damping, adjustable rebound and bottom-out control. Travel is 14.25 inches up front, and big Wilwood calipers squeeze oversized rotors.

GAS rules mandate an on-board fire extinguisher, and Jason chose Axia Alloys’ Quick-Release mount with a 2-pound extinguisher ($180.45). He also runs Axia’s 17-inch Panoramic rearview mirror ($166.20) with 1.5-inch arm mounts. Rules also mandate radios for communications with the safety crew and spotter, and Weller uses a PCI Race Radios Short-Course F1000 kit ($859.95) with two Icom 5-watt, handheld units; push-to-talk cable and button; a helmet kit; headset and Dirtbagz holder. He also has a PCI clean-air Compact Inline pumper ($89.95) and Impact helmet. Rules mandate a switch to cut power from the Full Throttle battery ($197.99), and the SR1 also has a Wilwood front/rear brake bias adjuster.

Those with a Rhino racing frame can convert to the R1-powered chain-drive engine with Weller’s complete mount and drive kit ($3,900) or a complete drive kit with big brakes ($4,300).

Weller uses an Aim MXS 1.2 Strada digital dash with speed, rpm, lap counter, lap time, gear, coolant temperature and oil pressure readouts. It has a high-contrast TFT color display and side RGB-alarm LEDs that can be set for shift points, GPS and track library, camera interface, and data download to a personal computer, all for $1,399. See www.aim-sportline.com or call (951) 674-9090.

Most short-course racing UTVs have front-width tires and wheels on the rear to boost handling and rotation in turns, but 2WD SR1s sport wider rear rims and 26×11-12 Maxxis Ceros tires for better drive. All in all, Jason’s Weller Racing SR1 Wolverine is a next-generation rocket and one of the fastest UTVs on the track. At GAS round two, Jason’s qualifying 51.193 lap time was faster than Trevor Leighton’s Pro 2 truck’s lap time of 51.945! Only the Pro Buggies were faster. 


Weller Racing, LLC

305 E Comstock Dr., Suite #8

Chandler, AZ 85225

(480) 507-4771


jaso[email protected]


See the 2022 Yamaha UTVs here: 2022 MODELS FROM YAMAHA – UTV Action Magazine

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