2004 Honda TRX450R

May 22, 2004
Story and photos by Eric Putter

2004 Honda TRX 450R

A Four-Wheeled CRF?

The all-new Sportrax TRX450R isn’t just another four-wheeler. It is the most highly anticipated and rumor-swirled quad of the past 15 years.

In 1989, Honda stopped production of its two-stroke FourTrax 250R. Since then, quad racers have been clamoring for the next-generation high-performance model. Why? Before the recent four-stroke revolution, the world-beating 250R was the basis for nearly every major-championship-winning racer for almost two decades.

Just as ATV enthusiasts were brooding over the 10th anniversary of the 250R’s demise, Big H unleashed the Sportrax 400EX, a four-wheeler that inherited the R’s awesome handling manners, but was saddled with a weak-willed XR400 motor. Honda loyalists begrudgingly accepted this stopgap model, modified the hell out of it and wondered when a suitable replacement for the mighty FourTrax might arrive.

A newfangled Thumper was inevitable once production lines for the CRF450R were stoked up in 2002. A serious, four-wheeled racer was not. When the bike hit, the ATV rumor mill exploded with supposed sightings of radical, aluminum-framed, full-on “RaceTraxes” powered by Honda’s Uni-Cam motor. The end result, of course, is much less radical, but groundbreaking nonetheless. With the Sportrax 450R, pundits got much of what they were looking for.

2004 Honda TRX450R
Even in 33-horsepower stock form, the TRX450R has enough gusto to wheelie up some of Glamis’ biggest dunes.

What they did get was a motor with the motorcycle’s basic architecture, re-engineered for the rigors of powering a 128-pound-heavier four-wheeler that carries a six-month warranty, the motocrosser comes with none. That said, more rigorous R&D and testing procedures were undertaken to ensure the ATV engine’s longevity. This powerplant looks nearly identical to the CRF’s, but to deal with the challenges of oil starvation while side-hilling, the engine cases’ interior webbing was totally redesigned for the ATV and oil capacity was increased. Surprisingly, the only interchangeable parts between the bike and quad are their cams and oil filters. The counterbalanced, SOHC, 450cc ATV mill has stronger gears in its five-cog box, a beefier clutch pack, a three-ring piston (instead of two rings), smaller steel valves (rather than titanium) in its four-valve head, a mellower 10.5:1 (instead of 12.0:1) compression ratio, a less radical camshaft, a 1200-rpm-lower redline (9800 rpm for the quad vs. the bike’s 12,000 rpm) and a 42mm butterfly-type carb with throttle-position sensor replaces the CRF’s racy flat-slide Keihin. 

Instead of a motorcycle-style aluminum perimeter frame, the new quad motor is housed in a not-so-radical steel chassis with a removable, aluminum subframe. Front suspension is provided by dual A-arms and fully adjustable Showa shocks that generate 8.4 inches of travel. In the only obvious nod to the FourTrax 250R, the TRX450 has a similar-looking cast aluminum swingarm. The arm is attached by another piggyback Showa damper, actuated by Honda’s patented Pro-Link setup, which provides 9.0 inches of travel. The chassis rides on a shortish, 49.2-inch wheelbase and measures out to sportquad-normal 46.3 inches wide.

2004 Honda TRX450R
The only styling clue grafted from its soul mate is the TRX’s cast aluminum swingarm. It looks nearly identical to that of the 1988-’89 FourTrax250R.

Looking around the new TRX, the latest in Honda’s Sportrax line of sport quads, it’s easy to see how it rises to Honda’s industry-leading level of trickness and intelligent design. Super-light, trick, aluminum items include the front bumper, front fender stays, shifter, brake pedal and rear grab bar. Braking hardware consists of 174mm discs and dual-piston, aluminum calipers up front; out back, a huge single-piston, aluminum caliper clamps a 190mm disc. A fat steering stem resides in front of a well tucked-in radiator. It’s readily apparent how Honda’s engineers sweated out the details: For simplified race conversion, the TRX front fender’s “ears” are held on with four easy-to-remove pop rivets and its LED tail/brake light pops off in seconds; engine oil is checked by a convenient sight glass; air-filter maintenance is a snap; the swingarm’s eccentric axle adjustment makes chain-slack fixes a breeze; the radiator cap is easily accessible, as are the suspension’s clickers and preload collars.

Honda loyalists didn’t get a reverse gear in its tyranny, like that on Suzuki’s LT-Z400, or the push-button electric starting seen on every modern four-stroke quad, including Yamaha’s radical, YZ-engined YFZ450 we tested late last year. The former is excusable on a serious sport quad, but the latter is not, no matter how easy the new Sportrax boots to life.

2004 Honda TRX450R
At just 350 pounds, the Sportrax is a well balanced and capable flyer.

Once a proper starting technique was established (thumb the carb-mounted choke lever when cold, push the bar-mounted hot-start lever when warm, stay away from the throttle at all times), the TRX mill lit up consistently, but all testers longed for a magic button every time they swung out the well-placed, forward-operating kickstart lever. 

Sitting on the long, narrow seat, the footpegs and handlebar comes naturally to hand, providing an ergonomically suitable package for riders of all sizes. From idle, a jab at the lightly sprung thumb throttle revealed a very quiet exhaust note. A quick row through the gears demonstrated the 450R’s excellent transmission, little engine braking and smooth rush of seamless steam, which dynoed out to just 33.1 horsepower at 7500 rpm, three ponies down on the YFZ. The Honda motor is strong down low, climbs nicely into the midrange, but signs off early. It’s new-school revvier than the 400EX’s ancient mill, but doesn’t build to a frenetic, YFZ-like crescendo with a big spike in its powerband.

Even with such mellow motor characteristics, when ridden aggressively, the Sportrax literally jumps out of corners due to its short wheelbase. In as-delivered, stock form, we also found the TRX rode a bit tall in the rear and stiffly valved at both ends. For our 150-pound main test rider, we removed all of the rear shock’s preload, enabling it to settle down further in its travel and let the back end transfer weight more effectively. His final suspension settings were two (of four) turns out on the front shocks’ compression and rebound clickers; 27 (of 35) clicks out on the rear compression and one turn (of three and three-quarters) on the rear rebound adjuster.

2004 Honda TRX450R
Although our stock test unit was shot in the dunes, it revealed itself to be just as competent in the open desert, flying around motocross tracks and cruising the trails.

Once set up thusly, the entire quad became much more plush and cooperative. The front end now turned in precisely and the rear transferred weight well. When charged hard into turns, its excellent brakes scrubbing off speed in a hurry, the neutral chassis flicks precisely through flat corners. The 350-pound quad’s air manners were just as good for fast trail riding and semi-fast laps on a motocross track as it flew straight and only bottomed when pushed too hard and too fast by too heavy testers.

Casual ATV riders won’t be disappointed with the TRX450. Stock versus stock, the Honda better suits less experienced riders due to its prodigious low-end torque, smooth powerband and plush suspension. The Sportrax deftly blows its immediate predecessor, the 400EX, into the proverbial weeds and has the class-leading YFZ well within sight. Serious racers will spend thousands of dollars modifying it, anyway, negating the Yamaha’s advantages.

So, did Honda bring all of the wild rumors of a full-race quad to life with the new Sportrax? Absolutely not, but the company did develop a suitable soul mate of the FourTrax 250R for the 21st century.

2004 Honda TRX450R
How far into the pack can the TRX fly at the racetrack when equipped with a few aftermarket goodies? Stay tuned to find out how our intrepid ATV editor did at grand prix and motocross events in a single weekend.

Hopefully, it won’t be another 15 years before Honda makes such a quantum leap. 

Share your thoughts on the ’04 Honda TRX450R in the MCUSA Forum. Click Here

In addition to his motorcycle-related duties, Putter, 40, a MCUSA regular, has spent “way too much time” in the past two decades riding, racing, photographing and writing about quads as an editor at some of the leading quad enthusiast magazines. 



Engine Type: 450cc liquid-cooled 4-stroke single
Bore and Stroke: 94.0mm x 64.8mm
Compression Ratio: 10.5:1
Valve Train: Unicam; four-valve

Check out the stock horsepower and torque curves of our bone-stock 2004 Honda TRX450R. Wait till you see what a little after-market goodies will do to this quad.
Check out the stock horsepower and torque curves of our bone-stock 2004 Honda TRX450R. Wait till you see what a little after-market goodies will do to this quad.

Carburetion: Keihin 42.0mm with TPS
Ignition: CD with electronic advance
Starter: Forward kick


Driveline: O-ring-sealed chain


Front Suspension:
Independent double-wishbone with Showa shocks, featuring adjustable spring preload, rebound and compression damping; 8.4-inch travel
Rear Suspension: Pro-Link with single Showa shock featuring adjustable spring preload, rebound and compression damping; 9.0-inch travel
Front Brakes: Dual hydraulic 174mm discs with twin-piston calipers

Do we like the 2004 Honda TRX450R you ask  Of course we do. But  it could use an electric starter and a few more ponies. Stay tuned as we bolt on a box full of go-fast goodies and race the bajeezus out of Big Red s four-wheeled ripper.
Do we like the 2004 Honda TRX450R you ask? Of course we do. But, it could use an electric starter and a few more ponies. Stay tuned as we bolt on a box full of go-fast goodies and race the bajeezus out of Big Red’s four-wheeled ripper.

Rear Brake: Single hydraulic 190mm disc with single-piston caliper
Front Tires: 22 x 7-10 knobby radial
Rear Tires: 20 x 10-9 knobby radial


72.6 inches
Width: 46.3 inches
Height: 43.6 inches
Wheelbase: 49.2 inches
Seat Height: 32.6 inches
Dry Weight: 350.0 pounds
Fuel Capacity: 3.2 gallons


Available Colors: Red MSRP: $6499


6 months

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