Duncan Racing TRX450R - First Ride

If you've ever raced an ATV, you're certainly aware of the three main ingredients needed to win: a good-handling suspension to keep you on all fours, a reliable motor with strong power to keep you at the front of the pack, and an intense physical conditioning and endurance to help you grab and hold that lead. Even though true physical fitness can't be bought, there are countless companies that offer parts that can help you obtain these very important ingredients. From engine kits to suspension systems, there are endless possibilities from which to choose. But as a consumer, there are many things to consider before purchasing parts and starting your build. We want to stress the point of making sure that you're buying good-quality parts, while considering the amount of maintenance that will be required once your build is complete.

Numerous companies can offer huge increases in horsepower output, but at what cost? Sure, your newly built motor puts out 35 horsepower over everyone else, but how ridable and reliable is it? How about your suspension? Just because a company offers a set of 2+1 A-arms and reservoir shocks doesn't mean those components necessarily perform up to par. In order to find out what it takes to build a high-performance racer that requires a minimal amount of maintenance, we called the legendary Loren Duncan of Duncan Racing International for his help and expertise. We asked Loren to fill us in on what it takes to create a high-performance quality racer that requires a minimal amount of time in the shop.

ATV Rider: Loren, when you were building this machine, tell us about the specific purpose or rider that you had in mind.

Loren Duncan: This bike is built as a highly competitive race machine for an amateur-level racer. We wanted to build a race machine that would feature the best balance of performance, reliability and value for the customer.

ATVR: What types of racing can a rider enter on this machine?
LD: This bike is designed to race both outdoor motocross and off-road races, with small minor changes, of course. The chassis isn't set up for cross-country woods-type racing, and the motor is too aggressive for a desert race bike.

ATVR: So what types of changes need to be made to this quad between the motocross and off-road races?
LD: The main changes that need to be done are the tires, wheels and gearing. Heavy-duty skid plates and a larger-capacity fuel tank with a quick-fill system are also recommended for off-road competition.

ATVR: In the engine department, what kind of modifications have been done and why?
LD: The engine is comprised of a DRI 450cc National Kit which features a Fat Boy 4 exhaust, JE piston, HP4 valve train kit, Vortex CDI unit and Pro Design Pro Flow air cleaner kit. The HP4 kit gives this engine a five-horsepower gain over stock. It's the main thing that sets our motors apart from those of our competition. The DRI HP4 feature Duncan Racing in-house cylinder head porting, Serdi valve seat machining, an MX grind billet camshaft (made in the U.S.A.), heavy-duty valve springs with titanium retainers, shortened bronze valve guides and oversize intake and exhaust valves.

ATVR: Does the piston supplied with this kit have higher than stock compression?
LD: No, the compression is increased over stock but is still kept at a manageable level. All of the engine modifications combined give almost a 17-horsepower increase over a stock machine. This offers riders a very fast and competitive engine that's still reliable and needs little maintenance. This setup doesn't require being torn down after every race like the [national pros] and is still relatively affordable.