REBORN CLASSIC: DUNCAN RACING/ROLL DESIGN LOBO TRX305R

A 25-year-old ATV racing icon is restored to perfection

By the staff of Dirt Wheels – Photos by Pat Carrigan

The PC 2000 2-stroke revs hard when needed but is much easier to push through the corners than a bigger bore engine. The lighter feel also makes it easier to ride.

When it comes to sport quads, it’s been said by many industry insiders that Roll Design’s Lobo is the best of the best, especially for West Coast racing. When you consider that very few new Lobos are manufactured today, the appeal of the legendary machine becomes even greater. “When you ride a Lobo, it’s like driving a sports car with short tires and fast steering. You don’t just cruise one; you’ve got to ride it,” says Loren Duncan, owner of Duncan Racing International. 

Lobo frames are hard to come by nowadays. “It’s just so time-consuming and cost-prohibitive. Right when COVID started, Doug Roll built a batch of two or three frames. I know, because we built two of them, and one was featured in Dirt Wheels,” said Duncan, who speaks reverently about working with Roll Design. The fit tolerances, attention to detail and hours upon hours of testing that go into every Roll Design product speak volumes, and Roll’s insistence on perfection means he has a hand in every frame and part that leaves his shop. “I’ve never had to use a hammer to put a Roll Design part together,” claimed Duncan.

This 25-year-old racer was originally built with Custom Axis shocks before Roll Design teamed up exclusively with Elka. The shocks were in excellent condition and only required servicing.

HOMECOMING

One of Duncan’s customers recently purchased a used Lobo. “This quad is a 1998 Lobo chassis built by Roll Design. The original customer bought it directly, and we built the motor—a PC 305cc. The original owner rode the crud out of it for 20 years. It just shows how much punishment these machines can take,” claimed Duncan. This Lobo eventually found its way home. Duncan continued, “Another client of ours bought it, and we did a ground-up restoration on it.” 

There have been many new innovations for sport quads since this particular machine was created over two decades ago, but it was decided to stick with what already worked. “Other than adding a GPR stabilizer, which wasn’t available for a Roll chassis at the time, we tried to keep it as true to form as we could, but we went through everything,” said Duncan.

At just 350 pounds, this Lobo weighs 50 pounds less than a 2023 Yamaha YFZ450R. It’s very light and balanced in the air and strong enough to brush off the biggest motocross jumps.

A SOLID FOUNDATION

“The chassis was in remarkably great condition,” claimed Duncan. Once the plastic fenders were removed and the chassis cleaned up, the prognosis was much better than expected. “We didn’t find any cracks in the chassis, and if you had seen this thing beforehand, you never would have believed it,” claimed Duncan. “Roll Design is just head and shoulders above the rest, especially on the vintage stuff.”

Parts that worked in 1998 aren’t necessarily what’s considered the best today, but Duncan wanted to keep this build historically accurate. “What was popular in the late 1990s was running 400EX front spindles, and this had those, so we kept 400EX spindles on it.” The original spindles were in excellent condition and just required some freshening up, which is good since these parts were discontinued years ago.

“I’m a huge proponent of Nikasil bores for heat dissipation and longevity. We’ve had PC cylinders finish races with no coolant… it’s the Nikasil.” – Loren Duncan

BIGGER ISN’T ALWAYS BETTER

“This motor package has been around for a long time. I can’t even tell you how many races these PC motors have won,” claimed Duncan. “We make four PC motors—a 275cc, which is just a big-bore bolt-on with stock cases. It’s even more reliable than a stock motor. And then, everybody likes big motors. We’ve got a 340cc and the new stroker 370cc,” said Duncan. “But, people get very misled and caught up in displacement, and the thing about the big engine is that it doesn’t rev, whereas the 305cc is super popular because it has a lot of roll-on torque, but it revs a lot better than the bigger-bore motors. It’s a little more versatile.” 

Duncan Racing engines are designed to endure the worst possible racing scenarios. “Our cylinders are Nikasil coated, while most everybody else is still running a sleeve. So, we’ve got a large flange on it, and we’ve got to bore the cases to set it on there,” said Duncan. “I’m a huge proponent of Nikasil bores for heat dissipation and longevity. We’ve had PC cylinders finish races with no coolant because there was an accident or a ripped hose; it’s the Nikasil. A steel liner would only make it a quarter of a lap,” claimed Duncan. The PC 2000 cylinder also allows for 25 percent more coolant capacity than a standard cylinder. “We tested these cylinders for two years before we sold them,” claimed Duncan.

If you go back and watch videos of Duncan Racing builds on the Dirt Wheels website, you’ll notice that each machine features an exhaust note that is strong and completely void of any flat spots, hiccups or backfires. It’s the details, like the DR SuperFlow mod on the Keihin 39 PWK carburetor, that take these engine builds to the next level. “We just cut any bell obstructions so that the air flows better through the venturi. We generally will use the 39 PWK [carburetor] for a little stronger mid- to top-end pull. The PC 2000 305cc build has good throttle response on the bottom, but it really comes to life between half and three-quarter throttle,” said Duncan.

Originally built in 1998, this Roll Design Lobo features a polished PC 2000 305cc power-valve engine with plenty of low-end grunt and fast-revving mid- to three-quarter range power.

SUSPENSION

We’re used to seeing Elka shocks on most of the newer Lobo builds we’ve featured in Dirt Wheels, but this Lobo was originally built with Custom Axis shocks when founder Mike Hallock ran Custom Axis. “These are the original shocks, which we went through and serviced, but they were in excellent shape.” The Roll Design Lobo A-arms and swingarm are designed for precise cornering and the abuse that motocross inflicts on pro-level ATVs.

These Custom Axis shocks are part of the original 1998 Roll Design build. They were still in excellent shape and only required standard servicing.

PRO RACER TEST RIDE

Our test ride took place on a private motocross track, which is best described as having more natural terrain with a combination of tight turns and fast flow. “The power is very linear and easy to ride without being super snappy,” said pro racer and frequent Dirt Wheels test rider Josh Row. “It has the new Vortex twist throttle from Motion Pro, and I was really happy with the throttle response and clutch engagement. It’s really strong off the bottom, especially with the smaller tires. These bikes are so light compared to the TRX450R that I’m used to. It’s really easy to flick around.”

The PC 2000 2-stroke revs hard when needed but is much easier to push through the corners than a bigger bore engine. The lighter feel also makes it easier to ride.

Now in his early 30s, Row isn’t old enough to remember a time when 2-stroke sport quads dominated the tracks, but he still appreciates them as much as the racers that were there. “I hadn’t ridden a two-stroke on a motocross track in a long time, but it was a lot of fun. The GBC Mini Master tires worked and handled the terrain well. Jump landings were super controllable, and the brakes worked great.”

The Roll Design/Custom Axis suspension combo also works great on or off the track. “The suspension handled really well, and all around, the bike felt super light and nimble. There were some good-sized doubles I was hitting, and it didn’t blow through the stroke at all,” said Row. “We also rode this same quad out at the Dumont sand dunes, and it was always predictable and, again, felt very light.”

In 1998, there wasn’t a steering damper available that would work with the Lobo chassis. Today, GPR makes a damper that will work, so it was added to the build.

PERFECTION COMES AT A PRICE

To build this same machine from the ground up today would easily push beyond $35,000. Loren Duncan has something to say to those that might balk at what it costs to build a Lobo. “I think some don’t appreciate the amount of time that goes into some of these vintage builds. You could be watching Barrett-Jackson, and a guy has 10,000 hours in a car. People can’t see it, but I can see it. There are 250 to 300 hours in this Lobo,” claimed Duncan. The motor alone is entirely polished, which took a tremendous amount of time and attention to tedious detail. 

“We’ve spent an entire day before just trying to refurbish a brake caliper, because you can no longer get the parts, and you’ve got to fix what’s there or make something that you don’t have,” claimed Duncan. “I’m restoring a couple of LT250Rs right now. Back in the day, I had all of the parts in stock. I could do a complete rebuild and transmission and have the thing in and out of the shop in a couple of weeks. Today, I’ve got to Time-Sert 20 holes. I’ve got to try to make the clutch washer work because they’re discontinued; it just takes a lot of extra time.”

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