RETURN OF THE HONDA TRX450R
— Making this popular quad new again —
By the staff of Dirt Wheels,
Photos by Pat “Ride in focus” Carrigan
There is no doubt that Duncan Racing International (DRI) helps breed winners. Erin Simmons relies on the DRI team of Loren and Leonard Duncan to build and prep his AZOP championship-winning Honda TRX450R. Going fast in Grand Prix-style racing is no small feat. Having a quad ready to tackle multiple types of terrain is half the battle of competition at a pro level. Simmons is no slouch on a quad, either. Winning races requires skill, determination, quick thinking, and a sprinkle or two of talent doesn’t hurt. We met with the DRI crew to test a few of their sterling builds, and Erin’s performance racer made the cut.
Erin needs a quad that is pro-level race-ready. Honda’s TRX450R continues to compete successfully in many types of competition. The motor can handle a lot of upgrades to produce more power while retaining reliability. Loren Duncan tackles the engine tear-downs, rebuilds, machining and more for the company. He massaged the Simmons motor with DRI’s National 450cc kit.
Loren used his vast experience to put together a JE piston, X22 Baja camshaft, valves with titanium retainers, valve springs, and valve guide kit that seamlessly work together. On top of that, he expertly ports and polishes the cylinder head, and machines the valve seats. He went a step further and had the crankshaft Cryoheat-treated to reduce friction and wear. The National 450cc kit also includes DRI’s Fat Boy 4 complete stainless steel exhaust system. Simmons wanted the muffler custom-anodized and powdercoated.
Once the top-end work was performed, the clutch was massaged. DRI uses its own clutch kit with a Hinson Racing’s clutch basket topped with a DRI quick-change clutch cover. Duncan’s oil cooler kit helps reduce engine heat and keeps power levels up with an assist from Maxima oil. Once the engine is completed, it’s handed over to Loren’s brother, Leonard, who handles chassis building. Leonard is also Simmons’ mechanic and preps the race quad for each round of racing. The engine was mounted in a freshly powdercoated TRX frame after a DRI gusseting kit was welded in. Powder 1 took care of the coating. Before the rest of the 450R was put together, Leonard installed a 41mm FCR carburetor that had a kit from DRI included. Next, a DRI-massaged Vortex X10 programmable CDI box was added. The intake system came from Pro Design with a custom-fitted K&N air filter. That finished off the power parts.
We aren’t surprised that Duncan installed Roll Design (RD) products on this build. Roll offers top-of-the-line suspension, steering and handling components for most ATVs. The stock steering stem was replaced with a +1-inch-taller RD anti-vibe stem. GPR’s V1 steering stabilizer tackles stabilization duties. Roll’s MX Lobo II A-arm kit was bolted onto the frame utilizing OEM Honda spindles. This kit adds width and more wheel travel than most aftermarket A-arm manufacturers. Roll utilizes Heim joints that allow you to adjust multiple facets of the kit’s alignment to match the terrain you ride in. Attached to the arms are a set of Elka Stage 5 fully adjustable shocks.
The rear end of the Honda gained the same suspension treatment. The new swingarm is a 1/2-inch longer than the stocker. Elka’s remote reservoir Stage 5 shock and linkage kit found their way onto the Honda. DRI installed the Crown Series steel braided brake lines to replace the stock ones. Leonard matched the new front width, with an RPM rear axle. The axle is very strong and allows you to change the width as required. RPM’s bearing carrier and anti-fade locknut were also used.
The suspension isn’t the most important handling component. Every piece plays a critical part in getting an ATV to move and steer how you want it to. Mounted atop the Roll Design anti-vibe clamp is a Fasst Company handlebar that utilizes elastomers to lessen vibrations and hard hits to the rider. Mounted to the bar on the left side is an Oury grip with a Works Connection clutch perch, hot start and lever combination next to it. You won’t find a control cluster for starting since the quad is kick-started. Powermadd Sentinel handguards protect the controls and Erin’s digits. On the right handlebar, a Motion Pro Vortex twist throttle is preferred.
Renegade race fuel feeds the thirsty engine and is contained in a large 3.7-gallon IMS fuel tank with a dry-break quick-fill setup. Pit stops need to be fast in racing, and a dry-break setup gets the job done in less than half the time. The OEM plastics were reused with a custom-made DRI/D’Cor graphics kit that show all of Erin’s sponsors, including his own father’s company, Antelope Slot Canyon Tours. Off-roading is in the Simmons family blood. The stock hood was replaced with a much more stylish FourWerx Carbon white plastic addition.
Heading downward, the stock seat was recovered with a Pro Top DR seat cover that adds a lot more grip for Simmons’ rear. On the front of the Honda sits a chrome DRI front bumper. Erin uses Roll Design nerf bars and heel guard/foot peg combos on his build for protection from other racers and great foot traction. Speaking of protection, the bottom of this Honda is covered by a 1/2-inch-thick Campbell Racing Fabrication skid plate. The rear brake rotor is guarded by a Hess Motorsports-crafted aluminum guard. One of our editors still runs that exact guard on his personal racer after two years of success. The new Sunstar rear sprocket and RK Excel chain is protected by a DRI aluminum guard.
Climbing aboard a built Honda TRX450R feels like home for us. Simmons’ Duncan-built ride was no exception. Everything worked together flawlessly. That includes the DWT beadlock wheels wrapped with renowned Maxxis RAZR 2 tires and filled with Tire Blocks. Once we grabbed a handful of throttle, and the tires found traction in the dry SoCal dirt, the DRI-built motor rocketed us away. The power output is quite potent but not overwhelming. The hit off the bottom is smooth, yet it has a much meatier midrange, and the engine continues to pull through the top end quite hard. We didn’t have any wet dirt to truly feel how strong the torque down low is.
Control is key for any machine, and a motor that is as easy to use as the suspension is supple is going to be a winner. The combination of Roll Design suspension and Elka shocks has won more races and championships than we can count. Erin’s Honda was able to soak up any terrain that we guided it to. Chop was soaked up, whoops were gobbled and landings were smooth. The quad corners just right for Grand Prix racing with enough clearance for rough sections, but it slides the rear controllably and easily.
Overall, Duncan Racing knocked another build out of the park and never ceases to impress. Their extensive experience is helping Erin Simmons transfer his great skills to the quad and win races! Stay tuned for more builds from their crew.
PARTS & CONTACTS
CAMPBELL RACING FABRICATION: (435) 632-4902, www.campbellracingfabrication.com
1/2-inch skid plate $110
CRYO HEAT: www.cryoheat.com
Cryo treatment & micro polishing $375
DOUGLAS WHEEL & TIRE: (800) 722-3746, www.dwtracing.com
Front & rear beadlock wheelset $749
DUNCAN RACING: (619) 258-6309, www.duncanracing.com
Baja frame prep $450
DRI National 450cc kit $2595
FCR 41mm carburetor kit $699
Oil cooler kit $995
DR-C14 clutch kit $199
DRI/D’Cor Simmons SE graphics kit: N/A
Quick-change clutch cover $199
Parking brake block-off $14.95
Chrome front bumper $199
Crown Series steel-braided brake lines:
ELKA SUSPENSION: (800) 557-0552, www.us.elkasuspension.com
Stage 5 front shocks $1,795
Stage 5 rear shock $1,295
Rear linkage $399
FASST CO.: (877) 306-1801, www.fasstco.com
Flexx handlebar $359.99
Bar pad cover $10
FOURWERX CARBON: (262) 501-9696, www.fwcarbon.com
Plastic hood $130
GPR STABILIZER: (619) 661-0101, www.gprstabilizer.com
V1 ATV damper kit $549
HESS MOTORSPORTS: (940) 759-4597, www.hess-motorsports.com
Rotor guard $150
HINSON RACING: (909) 946-2942, www.hinsonracing.com
Works IH/PP clutch basket $499
IMS PRODUCTS: (800) 237-9906, www.imsproducts.com
3.7-gal. fuel tank w/ dry brake $274.95
MAXIMA RACING OILS: (800) 345-8761, www.maximausa.com
MAXXIS: www.maxxis.com, local dealer
RAZR 2 – 21×7-10: NA
RAZR 2 – 20×11-9: NA
MOTION PRO: (650) 594-9600, www.motionpro.com
Vortex twist throttle $27.99
OURY GRIP: (800) 333-6879, www.ourygrips.com
Waffle grip $11.99
POWDER 1: (619) 588-9200, www.powder1.com
POWERMADD: (651) 462-8465, www.powermadd.com
Sentinel handguard $40
ATV mounting kit $45
PRO DESIGN: (714) 534-0620, www.prodesignracing.com
Pro Flow kit w/ K&N filter $169
ATV kill switch & tether $34.95
RENEGADE RACE FUEL: (800) 733-3381, www.renegaderacefuel.com
RK EXCEL: (760) 732-3161,
O-ring chain $85
ROLL DESIGN: (760) 731-5920, www.rolldesign.com
MX Lobo II A-arms $1595
+ 1/2-inch swingarm: N/A
+ 1-inch steering stem $299
Heel nerf bars w/ heel guards $239
RPM: (928) 771-9363, www.team-rpm.com
Dominator II axle $419
Bearing carrier $249
Anti-fade locknut $219
SUNSTAR: (937) 704-1462, www.sunstar-braking.com
Powerdrive countershaft sprocket – 14T $23.95
Rear steel sprocket, 38T $34.95
TIRE BLOCKS: (253) 973-5111, www.ridetireblocks.com
21×7-10 kit $100 a tire
20×11-9 kit $137.50 a tire
VORTEX IGNITIONS: www.vortexcdi.com
X10 programmable CDI $535
WORKS CONNECTION: (530) 642-9488, www.worksconnection.com
Clutch perch assembly
w/ hot start $189.95
Pro Top DR seat cover $199
SPONSORS: B&B Auto, Antelope Slot Canyon Tours, Duncan Racing, Roll Design, Elka Suspension, Fat Boy 4 Exhaust, RK, Hinson, GPR, DWT, Faast, Works Connection, CRF