DB’s Mark Tilley is rarely impressed with power, but came away from the Pro Circuit 60 flat jolted. He tagged it brutally fast, yet totally raceable.

There is no doubt that the ’09 Honda CRF450R is the biggest seller of the new year in the motocross market, yet it also holds the distinction of having a full-blown Jekyll and Hyde personality. Riders either love the linear, “cable hooked to the rear wheel” powerband, or wail at the lack of a hit. Pilots can worship the new nimble manners, the lightweight feel and the flickability; while the guy at the other end of the starting line is monumentally PO-d that he has 35 more payments on a machine that absorbs track garbage like a surfboard with a Kenmore refrigerator strapped to the nose. With these diverse qualities it’s quite apparent that the ’09 CRF450 will graciously accept input, updates, and lucky for you, Pro Circuit’s incredible engine and suspension mods.

Yes, the motor is big news, but PC’s suspension mods are excellent. Between our Pro tester and our bulbous older pilots, the mods softened the harshness, sponged up the big hits and improved cornering.

While we’ve been toying with fuel injection mapping updates (which really do help excite the powerband), and exhaust systems (which really do help transform the powerband), Pro Circuit’s owner and tuner extraordinaire Mitch Payton decided to by-pass the incremental changes and go for BIG. He reworked the head, ported for increased flow, modified the valve train and plopped on one of his Ti-4R titanium exhaust systems, all with the mindset to give the CRF450 titanic boost—everywhere! The Pro Circuit modified CRF450 makes 60 freakin’ horsepower, a mere ten-horsepower gain over the stock powerplant.

(Left) Internally, Pro Circuit completely reworks the cylinder and head on the CRF. A new camshaft, valves and piston kit are fit into cylinder porting that targets large gains—everywhere. Incredibly, it retains a totally smooth flow to the power—it’s just substantial! (Right) The full titanium Ti4R exhaust is an off the shelf design that is identical to what Pro Circuit fits onto their factory machines. It’s lighter, the dB level is totally legal, and the power gains are broad.

Incredibly, the 60 (which is what we tagged the machine) retains the good, linear powerband of the stocker. But unlike the soft whine that erupts smoothly and flows nicely into a good peak hit, the Pro Circuit “60” roars smoothly out of the hole. Then it snarls smoothly into the midrange, which is followed by a “smooth” knockout upper yank that had every single Dirt Bike tester howling with spaghetti plate sized eyeballs once they exited the track. Come on, we’re talking about 60 horsepower, and it’s hitless, linear, smooth, long and brutally effective.

(Left) New Pro Circuit triple clamps mirror the stock numbers, yet offer increased mobility through the bars and let us switch to the stronger Renthal Twin Wall big bar. (Right) Bones, performing valving mods inside the Pro Circuit box van.

Is the Pro Circuit mod for everyone? Let’s see, it’s just as rideable, mirrors the stock powerband, and makes great tractable power. The only difference between the PC 60 and the stocker is a slight gap in acceleration. The 60 plasters your pupils into your brain cavity, while the stocker feels like an enduro bike in comparison. At first it scared us. While it excited our Pro testers (which rarely happens), it took several days of acclimatization to learn how to manipulate the powerband to work to our advantage. Finally, we learned that we could short shift earlier and keep grabbing gears since the machine pulled it easily. This made for increased traction, faster lap times and a more relaxed gait to the suspension. The bottom line: we love the motor!

Ironically, the main reason for this story initially concerned the suspension, or more importantly the lack of balance to the new KYB dampers. We actually had three machines along for the test, which was done at Glen Helen’s National Track that has monumental hack, stunning jackhammer holes, and speed whack that will transform even the most subtle of handlers into a skateboard hitting speed bumps at a buck ninety.
Honda’s Ray Conway had already tested a Bones modified system that included stiffer springs both fore and aft (odd since everyone has been sniveling about the stinkbug feel and wanted to soften the rear spring rate), a Pro Circuit link (longer which in effect lowers the rear end), and valving that targeted plush, rather than stiff, when the attack mode is in effect. Both Mark Tilley (our top Pro tester) and the staff felt that the RC (not the redhead, but the Honda exec) spec was so good that had the machine come with it stock, it probably would have won the Dirt Bike 450 shootout. It was plush, stayed up in the stroke, cornered, tracked and felt planted in the turns. It got a rave yee-haw! Over two days and 14 hours of track time, Pro Circuit’s Jim “Bones” Bacon had us test between stock, the RC mod, and three combos that Bones felt would eradicate Ray’s pedestrian efforts as a tester. In the end, Tilley and the staff agreed on a combo that was mainly RC, a slight shaker of Bones and an inherent ability to grind on arm-jerking hack, retain plushness, and corner far better than the stocker we kept comparing it to.

The PC “60” is not only fit with a modified engine and suspension system, nearly every part from the triple clamps to the footpegs gets the Pro Circuit treatment.

(Left) Interesting dyno chart! Notice the pieced together grid necessary for the HP rating. (Right) PC spends a ton of time suspension testing and has perfected the art of removing the shock. They unbolt the sub-frame, leave the FI system hooked up and tweak the tail section out just far enough to remove the rear damper.

If you like smooth, a bit divey with a wandering vagueness to the front wheel stick, then the stock Honda CRF450R fits like a 13-year-old leather wallet. But if you prefer a volatile smooth that escalates with the effectiveness of a missile, fit with traction control via suspension that reacts, accepts and transmits contact under nasty duress, then the Pro Circuit “60” may rate as the MXer of the Year. It’s that good. Our bike is going to PC ASAP and we’re salivating—plain and simple.
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