WHAT COULD YOU DO TO IMPROVE THE 2014 YZ450F’S HANDLING? Thankfully, the major stuff that we did from 2010 to 2013 to make the YZ450F handle better, Yamaha did for us in 2014. Most notably, they moved the engine forward 10mm (7mm farther forward than we could with our limited backyard engineering), and they moved the radiators down on the frame (we used a DR.D lowering kit last year). That leaves four things that a YZ450F owner could do to make the YZ450F feel more accurate. (1) Shock linkage. We swapped out the stock, 142mm, rising-rate linkage for a longer 143.5mm Pro Circuit arm. This lowered the rear of the chassis, which eliminated the stinkbug feel of the 2014 layout. It also gave us more leeway in selecting the head angle best suited to the track we were riding on any given day. With the rear 8mm lower, we could slide the forks up to make the YZ450F turn sharper, but if we felt too much oversteer, we could slide the forks down in the clamps to slacken the head angle. Best of all, the longer link flattened out the chassis and made it feel more balanced. It should be noted that if you drop the rear of the 2014 YZ450F with a longer link, you should compensate by sliding the forks up 2mm and taking two clicks out of the low-speed compression. ( 2) Front brake. Why would we talk about brakes in this section when brakes are about stopping, not handling? Because it’s not true. Good brakes allow you to set the chassis into the terrain, initiate dive on the entrance to corners, and they hold the front steady on off-cambers. Brakes do more than stop the bike. Sadly, compared to the KTM’s 260mm Brembo front brakes, the YZ450F barely has any brakes. An aftermarket oversize rotor will not only stop better, but your YZ450F will handle better when you have the excess pucker power to make it do what you want. ( 3) Tires. The MXA wrecking crew is always amazed that a manufacturer will spend millions of dollars on engine design and chassis setup, and then throw a mediocre front tire on the bike. Yamaha did spec the latest version of the Dunlop MX51, but the MX51FA is just a workmanlike front tire. Most MXA test riders prefer a Bridgestone 403/404 combo or a Dunlop MX51 rear mated to an MX31 front.
albeit a little less irritating, our first mapping attempt was a copy of our 2013 Mellow map. This popular 2013 map retarded the ignition and richened the fuel down low. Unfortunately, it didn’t work on the 2014 model—at all. It made the stutter off the bottom worse and killed the power. Common sense told us that going richer on the fuel and retarding the ignition was the best remedy, but the best-laid plans of mice and men often go astray. Starting over, we borrowed a map from Yamaha test rider Travis Preston. One look at Preston’s map told us that it couldn’t possibly work. It was super rich and super advanced. How rich? It was 12 percent richer from idle to 3/8 throttle and 9 percent richer on top. Even more shocking was Preston’s ignition map. He had advanced the ignition 3 degrees in the lower quadrants and 2 degrees in the full- throttle and high-rpm quadrants. We were skeptical, but we tried it, and it worked. Yes, it felt rich, but the power improved across the board, and our major mapping complaints were lessened. Always scofflaws, we started making more maps, encouraged by the ease with which they could be programmed into the YZ450F’s black box. We made so many maps that on some of them, only one number out of nine was different. For some reason, our best map was Travis Preston’s map, with the exception of two different numbers on the low-end. Here is the map we ran:
FUEL MAP 4000 rpm 6500 rpm 9000 rpm 6/8......+ 3..............+ 3................+ 3 3/8......+ 4..............+ 4................+ 3 1/8......+ 4..............+ 4................+ 3
IGNITION MAP 4000 rpm 6500 rpm 9000 rpm 6/8......+ 2..............+ 2................+ 2 3/8......+ 3..............+ 3................+ 2 1/8......+ 2..............+ 2................+ 2
WHAT ABOUT MAPPING FOR AN AFTERMARKET EXHAUST PIPE? During our testing, we only tried a small number of aftermarket pipes, but strangely, they ran best with the stock 0, 0, 0 maps.