PROJECT ATV: Duncan Racing TRX450R Sand Slinger

Building a perfect duner is a matter of heritage, style and power preference. For years the Yamaha Banshee was the machine of choice for sheer power and its exhilarating ride. Oddly enough, with all the two-stroke resurrection we are seeing lately, the Banshee is not as popular as the Suzuki Quadzilla 500 or Honda 250R. The duner we are featuring this month was built around a newer Honda, the four-stroke TRX450R. Its owner, Thad Dirksen, let the legendary builder at Duncan Racing turn it into his perfect duner.

When you choose the Honda TRX450R to build any kind of hoppedup quad, you are probably first considering reliability. Honda has always been known as the most reliable, and when you take long rides into the depths of places like Glamis, you don’t want breakdowns. What you do want is handling, power, navigation and lights for around-theclock fun.


This project duner started life as a 2013 Honda TRX450R in fairly clean condition. Across the country you can find Hondas like this for around $4000 on the used market. Duncan put on their signature National kit, which ups the cc number to 470cc. It’s not a huge increase, but, again, reliability is key, along with performance. That additional 20cc, along with Duncan Racing (DR) head porting, titanium valve springs, a billet X11 camshaft and a 13:1 JE piston, brings the horsepower figures above 50 horsepower with a $2495 price tag. To get the most out of that new mill, Duncan Racing relied on the Fat Boy complete exhaust system ($649) and a Pro Design Pro Flow intake kit with K&N filter at $150. The carb has also been jetted fatter for extra fuel flow. To burn that VP race gas, Duncan has a secret weapon in the $539 Vortex programmable CDI box. DRI is the exclusive dealer of these amazing boxes, which they say are the easiest ignition and fuel programmers (EFI quads) on the planet to operate. You don’t have to take their word for it, because if you ask some of the top Supercross riders and the ATV national champion, Chad Wienen, what they use, it will be the same Vortex ignition. On this Honda, Duncan equipped it with a handlebar-mounted toggle switch that held two different ignition curves we could play with. Between the two, it was easy to tell the difference. Can you say third-gear wheelie? Well, one setting would allow for them, and the other was a broader, milder setting.


In the dunes, this Honda was a torque monster when you want to claw up steep bowls or drag race your buddies on the flats. Even with Skat-Trak paddles, you could start in second gear and race forward at an arm-jerking pace. However, if we just want to carve the bowls and ride the ridges or skim across the whoops, the milder Vortex setting would let you do it. Unlike any stock or built Banshee, this Honda was so easy to ride. You could cruise around all day in third gear and explore, or get aggressive and blip through all the gears having a great time. A full Hinson clutch made shifts super smooth and kept the power flowing to the eight Skat-Trak paddles. Mohawk 20×11-9 were used in the back, 21×710 were mounted up front, and DWT wheels were used on all four corners. Hook-up was never an issue. In fact, the eight straight paddles gave more than enough. With the front end planted, turning was light and predictable whether carving or side-hilling.


Surrounding the massaged and strengthened Honda powerplant was a freshly face-lifted stock frame with powdercoating from Powder 1 in Sand Diego, California. The stock swingarm was also bolted back in place, but not before an RPM axle was installed inside new tapered axle bearings. An Elka Stage 5 shock, along with linkage, was tucked below the rider. An OMF skid plate protected it all underneath. Up front a complete Roll A-arm setup was bolted on, along with a pair of Stage 5 shocks. This combo, along with Honda’s frontend geometry, is near perfection and works great for all riding applications.


In the sand, the Elkas floated. We rode after a big holiday weekend and the sand was choppy. The Roll Design front end and Elka shocks eliminated the small cross ruts and softened the big trenches. Usually, we would stay away from sections that are highly traveled, but with this setup we aimed for them. No matter if you rode at a cruising speed or wide open, the suspension soaked up everything. You could blitz the whoops of sand highways or wheelie across the smooth Glamis ridges just the same.


What was even more noticeable is when you hit the transitions between flat ground and a steep dune. The shocks would soak that up without causing you to lose any climbing speed. This way you could get up onto the higher bowls and spray roost over the top. More bump absorption on these transitions was provided by a Roll Design steering-stem-mounted GPR steering stabilizer. The stabilizer helps keep the bars from wandering when crossing ruts or running down them. The top of that stem was capped off with a set of Fasst Co. Flexx handlebars. These bars provided the last half-inch of cushion between the rider and the ground. They work great for reducing the harsh side-to-side hits when landing on one side or the other. The bars were equipped with a Works Connection clutch lever and perch, while the front-brake lever remained stock. However, the parking brake was removed and a DRI block-off plate was installed to protect the caliper. The throttle was changed out to a Motion Pro Vortex twist unit.


Along with a ton of extra power that performs how you need it and a suspension system that won’t wear you out, this quad was finished off with some accessories that help extend any ride. Up front a pair of $300 LED light bars from Rigid Industries were mounted on a custom DRI bracket. One was a spot that shot out far, so high-speed runs wouldn’t be an issue. But for pure carving maneuvers, a flood pattern was utilized as well. Closer to the rider’s view was a Lowrance HDS 5-inch Baja GPS unit. If you have been to a place as big as Glamis, you can appreciate the benefits of a GPS unit. With it, you can meander for hours without having to worry about finding your way back to camp. With this unit you can glance down and watch the map lead you, or just use it for a quick reference to know which direction to head. Or, better yet, use it to mark the best untracked dunes in the area for the next day’s ride. Either way, the Lowrance GPS was a great addition to the build.


Duncan Racing outdid themselves with this project. Although they used a lot of the same race-proven engine parts and suspension components their track stars use, they translated perfectly on this recreational ride. From the clean finish of the D’Cor Visuals graphics kit to the internals of the DRI National kit, we would be happy riding a machine like this in Glamis for years until the next popular dune machine takes over. And when it does, we bet Duncan Racing will have a hand in making it better. If you want them to make your quad better for any style of riding, give the DRI order desk a call at (619) 2586306. You can also see a lot more at


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