One of the great perks to this job is the availability of a wide variety of machines to ride, ranging from showroom stock to factory race-ready quads. When I walked into the shop at the ATVR headquarters and saw a brand-new customized 2008 Honda TRX450R, I was both surprised and anxious to give it a try. Longtime bike builder Jay Clark had contacted Editor Thad Josey about a new project quad he was working on which he thought our readers might enjoy checking out. He also wanted our feedback on the overall performance of this quad. Before I threw a leg over the shiny new Honda, I contacted Clark to find out what his objective was with this build. According to Jay, his goal was to create an all-around, do-everything ATV that offered a substantial power increase and improved handling on a reasonable budget.
The Build
Clark's statement in trying to achieve good power gains on a budget came in a variety of items. Internally the Honda received only two significant part changes, with the first being a Stage II camshaft from Hot Cams. This allows for increased air-fuel flow into the cylinder as well as exhaust flow once the engine has fired. To generate a strong torque curve, Clark sent the stock cylinder to Millennium Technologies to be bored out 2mm over stock and replated. This allowed him to install the 98mm CP piston that has now turned the mild-mannered 450 into a roaring 470. The new piston also features a 13.5:1 compression ratio over the claimed 12:1 stock unit, but we were assured it could still run on premium pump fuel. Feeling that these modifications would make a good deal of power, he opted not to have any port work done to the head.
In order to feed this new engine package the proper amount of fuel and air, Clark discarded the stock air filter system and replaced it with a high-flow Pro Design Pro Flow filter kit. In an attempt to increase throttle response, he turned to products from Scary Fast and Works Connection. The Scary Fast Power Now and Power Now Plus were installed to maximize airflow both to and from the carburetor, while a fuel screw from Works Connection and Powershot from Scary Fast were added to aid in dialing in the fuel delivery. To expel the exhaust from the high-flowing engine, an FMF SS PowerBomb header was matched up with a PowerCore 4 slip-on exhaust system. This combination again was chosen for its ability to make strong power through the entire range of the engine. With all of these motor modifications, this bike should be able to pull stumps out of the ground or at least effortlessly haul me around a track.
In the handling department, Clark turned to iShock suspension components. The iShock front suspension kit is 2 inches wider per side than the stock Honda A-arms and feature their exclusive CAS system which allows for caster and camber adjustments to be made in seconds without the need to remove the front tires. These kits also come with the iShock M1-A6 long-travel front shocks in addition to everything else you need to install the kit, such as brake lines, a ball joint removal tool and even an instructional DVD. The M1-A6 shocks feature high- and low-speed compression, rebound and preload adjustability and are 100 percent rebuildable.
To complement the suspension performance at the front of the machine, the stock rear shock was completely torn down and received a complete rebuild/revalve from the tuners at iShock. To even out the width from front to back, a DuraBlue X-33 pin-drive axle was installed into the stock swingarm and bearing carrier. Not only is the X-33 axle wider than stock, but it is less prone to bending and breaking by its amazing strength. Transferring the power to the ground was done with Dunlop Quadmax Sport Radial MX-01 tires mounted to DWT Racing Ultimate front and rear beadlock wheels. This tire/wheel combination is almost identical to what you would find many professional racers running on their machines in some of the most demanding terrain.