Jimmy Wood pitches it deep...
Jimmy Wood pitches it deep enough into a corner to make a mortal's head explode, scrubbing off just enough speed to hold his line with a little front end push at the apex. Yikes!
How to Get Sideways Without Going Broke
2 Yamaha YZ450F Dirt-Tracker
Flat-track is something like sculpting redwood with a chainsaw. It looks easy...until you strap on a steel shoe and try it yourself. But for those of us who idolize Scotty Parker, Jay Springsteen and Chris Carr, the hardest part can be finding a suitable tool to try it with--something less intimidating than a purpose-built $20,000 Harley-Davidson XR750, but more capable than your average dirtbike.
But what?
"I tell people who want to get into flat-track to start out with a motocross bike," says Jimmy Wood, who rides this artfully converted #37 Southland Racing Products Yamaha YZ450F. "Take the back rim and throw it on the front; then all you really need is a [wider] 19-inch rear rim and a spoke kit. Lower the fork and shock, put on a set of dirt-track tires and you're pretty much ready to go."
Lower speeds make short-track racing easier to wrap your mind around than the larger half-mile and mile ovals. Especially when you can convert a 450cc motocrosser into a competitive short-tracker for about $1600 tacked onto the price of a new (or used) bike.
The parts list gets longer for someone like Jimmy, who contends the fiercely competitive AMA Grand National Singles series from Daytona Beach, Florida in March to Springfield, Illinois in September. Still, converting a modern four-stroke motocross bike is easier and a whole lot less expensive than bolting said engine into a purpose-built steel tube frame and waiting for the UPS man to deliver a laundry list of esoteric essentials from all over the country.
Despite being 30-35 lbs. lighter than Wood's converted motocrosser and wickedly fast under someone with the skills to wield one, the pure-bred, $16,000-plus "framer" is also irrelevant in the AMA GNS Championship. According to the 2009 rulebook, the main frame and swingarm must be stock. "Last year you could ride anything you wanted at the Nationals," says Wood. "At Daytona, everybody had a framer. The track is slippery and bumpy, so you need something with a lot of grip. There wasn't one stock frame in that main event. Then at the end of the year we went to Springfield, where there's a whole lot of grip, and everyone was on a stock frame."
 Coming to grips with the Yamaha...  Coming to grips with the Yamaha YZ450F short-tracker on a slippery Willow Springs 3/8-mile oval is all about assuming the correct body position and being smooth on the throttle. |  |  Wood's bike showed up at Willow...  Wood's bike showed up at Willow Springs on Maxxis dirt-track rubber. AMA rules mandate Dunlop CD-5 and CD-8 tires. |
Though it looks more like a slammed motocrosser than what Jim Rice and Gene Romero rode in On Any Sunday, Wood's Yamaha is much more accessible in every sense of the word. Start with the engine: A stock YZ450F makes about 50 horsepower. This one makes 59, thanks to a Rocket exhaust, bored stock carburetor, new cams and valve springs, higher compression, a ported cylinder head and assorted other top-end tweaks from Jim Wood--a.k.a. Jimmy's dad--the one-man brain trust behind Southland Racing Products in San Bernardino, California. He'll add a few more horses for faster tracks like Peoria, but smooth, linear power is the key. And the Yamaha's bottom-heavy power delivery is a good place to start.
The stock YZ450F hits hard and trails off quickly--perfect for point-and-shoot motocross tracks, but not the best for sliding around a quarter-mile short-track. Wood's version draws a straighter, more linear power curve that translates to controllable acceleration out of slippery corners. Adding 60 ounces to the stock crankshaft--the most extra metal you can stuff into the stock crankcase--smoothes out the power delivery to improve grip, but it's expensive: $450-$750 depending on how much weight you add. "The heavier flywheel lets me turn it on harder in the middle of a corner and it'll grip better at the exit, but the bike doesn't accelerate as hard," Wood explains. "And when you shut it off at the end of the straightaway, it doesn't want to stop." A simple Yamaha GYTR bolt-on flywheel weight adds 30 ounces that make the stock bike's 50 horses easier for most riders to use.
The Southland Racing Yamaha...
The Southland Racing Yamaha YZ450F makes about 9 more horses than stock. Critically for a dirt-tracker, that power is more linear.
Flat-track is all about grip, and the engine is only half of that equation. The other half of convincing a motocrosser to steer with the throttle and slide on cue starts with moving everything closer to the ground. Jim Wood says shortening the fork by 5-6 inches and the shock by 1-1.25 inches puts the YZ in its short-track happy place. More than that and the bike stands up mid-corner; any less and the rear wheel spins instead of putting power to the ground. The short-tracker's springs are 25-30 percent stiffer and damping rates are firmed up considerably.
Rubber-covered footpegs are essential when you're wearing a steel shoe on one foot. Armed with a set of Dunlop or Maxxis dirt-track tires, you have a tool that's good enough to win if you are.
After a few dozen laps around the Willow Springs half-mile, we had a pretty good idea of what it takes to be a dirt-tracker. Cojones like Brunswick bowling balls, for starters: With no front brake, engine braking and sideslip slow you down going in--try to ignore that fence around the outside. Snap the throttle shut and the front end wants to wash out. Roll it off gently and the bike tracks to the apex, at which point you dial it back on and drive off the corner. In too deep? Closing the throttle just makes things worse. You've got to get the back end sliding to get the front end pointed toward the bottom of the racetrack. Yes, it's counter-intuitive at first. It's addictive too. And the only known cure is topping off the tank for another dozen laps.
Yamaha YZ450F Dirt-Tracker
What You Need
19-inch wheels with dirt-track tires, lower/firmer suspension, heavier flywheel, rubber-covered footpegs
What A Pro Needs
Motor work, exhaust, adjustable triple clamps, quick-change rear wheel, gearing (13-15-tooth countershafts, 40-50-tooth wheel sprockets)
How much?
$9000 to go get sideways $14,000 to line up with Jimmy Wood et al