This 450 supersingle was built using a 2005 CRF450R in late 2007-early 2008 with the intention of running it in the newly created WERA 450 supersingles class. The bike was built in collaboration with Hyperformance Cycles in Woodstock, Ga. The shop owner, Mark Klein, is well respected in the area for his work, especially with dirtbikes. I have 6 race weekend and 3 full trackdays on the bike so far, not counting the upcoming WERA GNF. I originally ran it at WERA nationals in the 450 supersingle class in 2008, but in 2009 I have run Clubman and D Superbike as well.
Starting off, we stripped the donor bike down to the frame, swingarm, and subframe. For reliability sake, we rebuilt the motor with a mild supersport build and all new top end components. The rear wheel was sent out to be re-spoked to a 5”x17” rear rim. The front end was relatively easy to bolt up, considering what we were doing with it. The 600RR and the CRF450R stems are the same size, so we pressed out the 600RR stem and pressed in the 450 stem to bolt the lower triple clamp on the 450 frame. I had to enlarge the hole in the upper clamp by an additional 2mm. Once that was done, the front end could be attached to the bike. We lengthened the forks internally to give the bike a little less radical front end geometry. In addition to the length, the forks were revalved and resprung for the lighter bike. The rear shock is still the stock CRF450 unit. However, I machined an internal spacer to shorten it by about half an inch and bought a more appropriate spring for it. Mark was able to revalve the shock to match the stiffer spring.
The bodywork is an assortment of a Honda RS250 upper, bellypan, and tailsection, a 600RR front fender, and a 1000RR tank cover. Everything but the front fender required some minor trimming for fitment (i.e. chain, clipons, exhaust, etc…). I made brackets out of an assortment of resources. The upper fairing stay actually came from a spare FZR600 upper stay. I fabricated the other brackets out of aluminum and/or stainless steel sheetmetal. The exhaust itself is a custom piece made by Britt Lynn using mandrel bent 304SS. The muffler is a shortened Leo Vince Ti unit. Dyno tuning was done by Rod Burr at MSP cycles.
The ergonomics and controls were the last few parts that required some fabrication. The clipons are Woodcraft 600RR units and the rearsets are from the 2006-2008 model R6 (also Woodcraft). I machined rearset adaptors from a 3/8” thick plate of aluminum and then bent the plates in order to bolt them to the subframe upper mount and original MX footpeg lower mount. The shift linkage is made from an L bracket attached to a chopped stock pedal that had the proper spline pattern. GP Tech now makes a shift linkage that makes the whole process much easier.
Specs:
2005 Honda CRF450R
Weight: 241 lb wet
Max Power: 45 hp @9000 rpm
Torque: 34 ft-lb
Suspension Front: 2007 CBR600RR inverted forks, lengthened, re-valved and resprung
Suspension Rear: 2005 CRF450R rear shock, shortened, re-valved and resprung
Wheels: F 3.5”x17”; R 5”x17”
Brakes: Single 310mm rotor and radial mount four piston caliper from a 2007 CBR600RR, Brembo 16×18 Radial Brake Master Cylinder
Exhaust: Custom unit by Britt Lynn
Controls: Woodcraft CBR600RR clipons, Yamaha R6 rearsets with custom adaptor plates
Bodywork: Sharkskinz RS250 upper, lower, and tail: CBR600RR Front Fender, 1000RR Tank Cover. Paint by Mike Buffington
