timing (to help burn the extra fuel). The caveat is that our dyno runs and testing have been done with different mapping from stock. Q: HOW DOES THE 2014 YZ450F RUN ON THE DYNO? A: Maximum horsepower on our 2014 YZ450F was 58. 17 ponies. That makes it the most powerful 450cc production engine we have ever tested, besting the previous horsepower leader, the 2013 KTM 450SXF, by more than a horsepower. You can take this to the bank: the 2014 Yamaha YZ450F dyno curve is a parabolic thing of beauty. It climbs without any of the dips of last year and keeps on going until the cows come home (once it is remapped). Q: WHAT IS THE RELATIONSHIP BETWEEN THE ENGINE AND THE CHASSIS? A: If you put on your thinking cap and stand back, you can see that the overall design of the Yamaha engine isn’t solely about producing power, although it does that in grand fashion. In truth, the slant-back YZ450F engine was conceived to make the YZ450F handle better. To learn more about how this works, turn to page 42. Okay, we admit that from 2010 through 2013 the han- dling benefits of the unique engine design were muted by issues with a front-end push that was aggravated by the barky low-end hit. The front would wiggle going into a corner, and the bark would lift the front on the exit—not a confidence- building combination. Not surprisingly, the best fix for the 2010–2013 handling was to remap the engine to eliminate the bark and add a flywheel weight to tame the lift. These fixes aptly highlight the crossover effect of power delivery on chassis dynamics. The chassis and the engine are not independent entities but work in unison, else they work against each other. Q: HOW DOES THE 2014 YZ450F HANDLE? A: The handling is better in 2014 than it was in 2013, but in a way that is kind of disappointing. When a manufacturer goes all in on a new design, it is human nature to assume that it will be better on all fronts. So, we enthusiastically expected every aspect of the 2014 YZ450F to blow our socks off. The 2014 YZ450F didn’t do that. Most MXA test riders complained that the bike had a stinkbug feel. The high-in-the-rear and low-in-the-front stance steepened the head angle enough that the front wheel hunted and pecked on the entrance to turns. We opted to run 105mm of sag to bring the rear of the chassis down, but this isn’t the optimum fix, because you are compromising the rear suspension to band-aid the chassis. Eventually, we settled on a 1.5mm-longer shock linkage and a better front tire for our terrain. The YZ450F rolls off the showroom floor with the new Dunlop MX51FA (the upgraded brother of the less-than-stellar MX51). Neither the MX51 nor MX51FA would be our first tire choice for intermediate terrain, and especially not for a bike with a loose-feeling front end. Q: WHAT DID WE HAVE ISSUES WITH? A: The MXA wrecking crew had some problems during testing. These were our main concerns: The gearbox. Yamaha lowered third gear to close up the gap between second and third, which has been a bugaboo for a few years. Unfortunately, they also changed the primary gear ratio to move all the other gears up. The result? While the gap between second and third is closed up, the gap between third and fourth is widened. To help mitigate the problem the new primary gear created, Yamaha installed a 49-tooth sprocket in place of last year’s 48, which allowed the 2014 gearbox to mimic last year’s 48-tooth gearing, but did nothing for the new gaps. At every race, the MXA test riders carried a quiver of sprockets—from 48- to 51-teeth—to allow each test rider to choose what he wanted to race with. In the end, the consensus was the 50-tooth sprocket. The mapping. The GYTR Power Tuner has room for 10 different maps— and we used every one of them. In the end, we settled on a version of the “Travis Preston map.” Preston did the development riding on the YZ450F during the pre-pro stage and came up with the map that we elected to run, even though it was rich on fuel and advanced on ignition. You can see our modified “Travis Preston map” on page 42. Brakes. What brakes? Has anyone at a Japanese motorcycle manufacturer ever ridden a KTM? If not, they should, because that is the gold standard of braking performance. The Honda, Yamaha, Kawasaki and Suzuki are closer to the lead standard. Q: WHAT WERE THE HIGHLIGHTS OF THE NEW YZ450F DESIGN? A: There is no doubt Yamaha listened to consumers when it came time to redesign the YZ450F. Here are the bright spots. Airbox. We hated the old airbox design with a passion. It required taking the bike apart to get to the King Why-Zed: This is the most powerful 450 engine made.