When the 12 Hours of America race moved to Texas last year, the course layout meant it would be much faster than in years past and begged for a big motor. An open-terrain race equals a horsepower battle, and the logical choice led CT Racing to the Yamaha Raptor 700R. With a proven long-distance track record using the venerable Honda TRX450R-including the last two SCORE off-road championships and a 2005 Best in the Desert title-CT had enough experience to take a crack at endurance-racing the Raptor.
As on their Baja quads, the crew at CT Racing was able to do a conservative build job, yet still develop massive power with this Raptor. It spits out over 60 horsepower and nearly 50 foot-pounds of torque, measured at the rear wheel-something not possible from a 450 without reliability issues, which are not good in off-road racing.
MotorTo achieve these impressive numbers, CT Racing started from the top, porting the head and unleashing its high-tech Newen CNC contour valve machine to tie the porting into a five-angle radius valve job, as many NASCAR teams are currently doing. Next, a Web Cams Sonic-grind camshaft and Web valve springs with titanium retainers were added. CT avoids heavy valve springs on its builds when possible; they add drag, as the motor must overcome the added spring pressure and quickening wear on the valvetrain. In this case, it was a necessary evil to work with the high-lift cam.
A JE 13:1 piston was picked to make this thing bark out of the corners. However, the high-compression piston mandates burning a minimum of 100-octane fuel. If this race had long straights like the dry lake beds and fast roads of Baja, the compression probably would have been dropped to 12:1 for the extended, wide-open throttle periods. CT uses VP Racing Fuels' C12 (because that's what the shop stocks), and the motor was tuned around this race gas. VP has several other fuels that would work well, including Ultimate 4 and both leaded and unleaded packages.
Keeping the air-fuel mixture just so is a Dynatek fuel injector controller. The Dynatek system is one of the easiest to tune; it can be adjusted with just a flat-blade screwdriver. A Dyna FS ignition module controls the ignition and eliminated the speed sensor-built into the Raptor 700R's ignition as a safety device. These electronics enabled CT's Allen Knowles to tune the fuel management to match the motor work. A Pro Design Pro Flow foam filter kit kept the motor and throttle body from inhaling any dirt in its big gulps of clean air. The final touch to the power game was the tunable CT Sonic exhaust system (the same system that worked well in our Raptor 700 pipe shootout in the March '06 issue). The key is the reverse-cone megaphone-style pipe tuned with the disc system. This not only puts out big power but is spark-arrested. This unit was set up for closed-course racing so it was a tad louder than we like, but the good news is noise level can be adjusted to meet local sound requirements by simply removing discs. Before everything was buttoned up, a Hinson clutch basket was installed to eliminate any chance of clutch failure.