EXTREME FABRICATION BIG-WHEEL YZ450F
REVISITING THE DECEMBER 2015 ATV ACTION FEATURE
Way back when this magazine was called 3&4-Wheel ATV Action, I came on board as Associate Editor the same year Yamaha introduced its revolutionary Big Wheel BW200N two-wheeler ATV. The 1985 BW200N was an absolute hoot to ride, and then-Editor Steve Casper and I would set up courses in sand washes and race for hours on end. Rain or shine. For 1986, Yamaha added the BW80S, a fat-tired PW80, and an electric-start BW200ES, and the kick-start BW200 was dropped by 1987, which was the year Yamaha went big with the BW350T. I loved the BW350, an awesome wheelie machine, and it was a thrill to wheelie it seemingly forever on Estero Beach in Baja. I even raced it at an arenacross race in Bakersfield. It was only Crashper and I signed up, so promoters put us in with the Open Novice bike class. I hole-shot and led the race until some yahoo ghosted his brand-new Husqvarna 500 into me and took me down. The BW350 had a lot more power than the 200, but it was still lacking by today’s standards. In 1988, all three Big Wheels were produced, but none were made in 1989. The BW80 returned in 1990, but that was its last year.
BIG WHEEL REBOOT AND UPGRADE
Extreme Fabrication Racing (XFR) in St, George, Utah, missed Big Wheel Yamahas as well, so they decided to bring it back with a new twist. Instead of a low-tech engine from the old Yamaha Warrior 350, why not use the modern version of the engine that spawned the four-stroke revolution, the 1998-1999 Yamaha YZ400F? Extreme Fab set out to develop Big Wheel kits for the YZ426F through the YZ450F. XFR built a wider swing arm for an 11-inch-wide rim and incorporated a jackshaft on a concentric shaft for chain adjustment. XFR then machined the rear hub out of a 35-pound chunk of billet aluminum and also machined the hub to accommodate the OEM Yamaha YZ450F brake rotor and sprocket. Heavy-duty bearings are used in the billet-aluminum hub, and the billet AMS wheel was fitted with a Carlisle AT489 24×11-12 for our hard-pack terrain test.
Up front, the stock triple clamps were removed, and wider clamps were machined from solid billet aluminum. The dirt bike we rode was a 2010 YZ450F converted to Big Wheel using the OEM forks, and the final design will have the fork clamps moved to the inside for more radiator clearance. XFR machined a new front hub with double-wide bearings and mount for the OEM YZ450F front brake rotor and caliper as well as the AMS billet wheel. For hardpack, XFR fitted a Kenda Pathfinder 25×8-12 direction tire. In all, the Big Wheel kit for 2006-2009 Yamaha YZFs has 70 parts, not including tires and wheels, for $2,899.99 (It was $2590 in 2015). There are also kits for 2002-2022 WR450Fs and YZ450Fs for $2,899.99. Does that sound worth it to shred dunes and desert with a 60-Hp ATV?
RIDING THE BIG WHEEL 450F
We got Charlie Ogden, a local Pro rider who races a Honda CRF450R, to ride the XFR Big Wheel 450F, and he ripped up the Paiute UTV Jamboree King of the Trail obstacle course for photos. He felt fork spring rates were a little soft for his riding style, but he looked good on the Big Wheel. I got to ride the Big Wheel as well, and all those Big Wheel memories came back. How cool it would’ve been to have this sort of power with those old Big Wheels, but, then again, those machines couldn’t touch the sophisticated long-travel suspension, aluminum perimeter frames, giant hydraulic discs brakes, liquid cooling and EFI-induction of the modern 450s. We also got a chance to ride another XFR Big Wheel shod with sand tires and made a few new Big Wheel memories in local sand washes and at Oceano Dunes SVRA at Pismo.
Extreme Fabrication Racing
731 Industrial Road
St. George, UT 84770