What is the definition of flat? Flat powerbands, like the CRF450’s, build power up to a certain point (in this case, 8000 rpm), and then don’t gain any more horsepower as they rev. And while the 2010 Honda will rev all the way to 11,2000 rpm, it hangs at 50 horsepower for the 3000 rpm range above its 8000 rpm peak power point. Flat engines require short-shifting or, more accurately, shifting just short of peak. If you try to rev the engine beyond peak, you will be rewarded with lots of noise, but not much thrust. As a rule of thumb, the Honda CRF450, RM-Z450 and YZ450F are flat on top (to varying degrees). The KX450F and KTM 450SXF are not flat. Q: DOES THE 2010 CRF450 PASS THE AMA SOUND TEST? A: No. At 96. 7 dB, the 2010 CRF450 cannot meet the AMA’s 94 dB limit (even with the generous 1.9 dB correction factor).Q: DOES THE CRF450’S EFI SYSTEM SUFFER FROM FLAME-OUT? A: Yes. Flame-out is when the engine quits suddenly at low rpm. Fuel injection does not seem to be as adept at handling throttle chops as efficiently as a carburetor. Try turn- ing the idle up, but a fast hand on the clutch will still be required. Q: HOW IS THE GEARING? A: We geared it down one tooth. Q: HOW DOES THE 2010 CRF450 HANDLE? A: The MXA wrecking crew’s opinion of the CRF450 chassis is well-known. We think that it has some serious issues with balance, stink bugging, soft forks, oversteer and sketchiness at speed. The short answer is that we don’t think the 2010 CRF450 handles very well in stock trim. Balance. The front forks are way too soft. This allows the front end to dive under deceleration. This is at odds with the firmer feel of the rear shock. Stinkbug. As it rolls off the showroom floor, the CRF450 sits at a stinkbug stance (front down and rear up). Soft forks. The soft forks aggravate the steep 26.52- degree head angle. When the forks compress under braking,
the frame’s head angle ventures into trials bike territory. Oversteer. Because of the chassis’ setup, the front of the CRF450 is amazing at turn-in. Even the slightest movement of the bars will initiate a turn, but it is too much of a good thing. The front tire oversteers in, which requires a counter-steer correction, which results in a wallowy front end. It can make a simple left-hand turn into three or four distinct movements of the bars. Sketchiness. When you combine a steep head angle with soft forks and a stiff rear shock, you get a very busy bike at speed. Q: WHAT WERE OUR BEST FORK SETTING? A: One of the surprises of the 2010 forks is that while they are seriously undersprung, Honda did a good job of increasing the low- and mid-speed damping. Plus, Honda raised the oil height to firm up the end of the stroke. It is a noticeable improvement, but not enough to hold the forks up at race speeds. At the bare minimum, these forks need stiffer fork springs. For hardcore racing, these are MXA’s recom- mended 2010 Honda CRF450 fork settings. Spring rate: 0.48 kg/mm (0.46 stock) Oil height: 355cc Compression: 6 clicks out ( 13 stock) Rebound: 8 clicks out Fork leg height: Flush with clamps Notes: If you want to keep the stock fork springs, slide the forks as far down into the triple clamps as possible to raise the front of the chassis. Q: WHAT WAS OUR BEST SHOCK SETTING? A: We loved the new shock valving (although with the soft forks it is hard to get a good read on how well the new shock works). You will never get the shock to live up to its potential until you stiffen up the front forks. For hardcore racing, these are MXA’s recommended 2010 CRF450 shock settings (for the stock setup). Spring rate: 5. 4 kg/mm Race sag: 115mm Hi-compression: 2 turns out (1-1/2 stock) Lo-compression: 11 clicks out Rebound: 15 clicks out ( 14 stock) Notes: As it rolls off the showroom floor, the stock shock needs to have the race sag set as low as possible (thus the recommended 115mm of sag). This isn’t done to make the shock work better, since eating up travel and Mellow: The ECU map has been tamed down for broader power.