Q: WAS STEWART WRONG ABOUT THE YAMAHA YZ450F? A: Not for him. Bubba had lost confidence in the JGR YZ450F, and for a professional athlete, confidence is a major factor in his ability to perform. But Stewart’s troubles are incidental to MXA’s interest in the 2013 YZ450F. He is a highly paid professional rider who has to make the moves that he thinks are best for his career. And, in his defense, MXA has its own complaints about the 2010–2013 YZ450F chassis. It has a loose feel on the entrance to turns that displays itself as a wiggle. Its abrupt power delivery lifts the front end under acceleration, and the combination of no weight on the front and the loose sensation at turn-in causes the front end to push at the least opportune times. Q: IS THERE A QUICK FIX FOR THE 2013 YAMAHA YZ450F’S HANDLING? A: Yes. Taming the manners of the YZ450F all boils down to proper setup, which is why James Stewart could not get on with it. The MXA test riders’ main goal with the 2013 Yamaha YZ450F was to adjust the ride height, fine-tune the suspension and balance the bike to keep the front wheel planted in the corners. We also tuned the powerband to maximize grip from low to mid—even if it meant sacrificing pure power. Some of MXA’s mods are simple and some are complex, but they all cost money. Q: HOW DO YOU MAXIMIZE THE YZ450F POWERBAND FOR GRIP? A: First, you need to accept that the 2013 YZ450F— and by association the 2010–2012 YZ-Fs—is more hard- hitting than super fast. The backwards engine is very barky and abrupt off the bottom. Although it makes very good horsepower on the dyno, it is basically a low-to-mid engine on the track. The aggressive power off idle makes it a holeshot machine, because it literally jumps off the line; however, that abruptness means that it also jumps out of ruts and tight turns when you don’t want it to. The MXA test crew made a series of mods, some that contradicted each other, with the full understanding that motocross setup is a dance with many intricate moves. Here are our four major mods. (1) Gearing. We geared it down from a 49-tooth sprocket to a 50. Yes, we knew that lowering the gearing would make it more abrupt, but we had other ways to handle that. We geared it down to get to third gear sooner, tighten up the gaps and ease the pressure on the upshift from second to third. ( 2) Mapping. We remapped it. We tested five different maps to try to find the best combination of power and drive. Shockingly, our Pro test riders preferred the richest and most retarded setting, while the Novices and Vets opted for less extreme ignition and fuel settings. Either way, we retarded the ignition and richened the fuel down low to eliminate the bark that hampered cornering. Without the violent hit off the bottom, the front wheel didn’t get light under acceleration. Our only explanation for why our faster test riders preferred the most retarded ignition and fuel settings was because they carried more speed and didn’t need the bark to get going. The slower test riders also retarded the hard hit, but left a little more of it since their exit speed was slower.
2013 Yamaha YZ450F: This bike is defined by
two attributes. First, it has the best showroom
stock suspension and, second, it is bulletproof.