One look and you know all this bike wants to do is piss off like a scalded cat. That alone makes it cool. But the coolest thing about this Gregg's Customs R1 Tracker is that it does piss off like a scalded cat.

After a few corners, a few rips on the throttle, I forgot about the trepidation I always feel when throwing a leg over a one-off custom like this. Any worry about the time, effort, creativity and money that went into building this exquisite-yet-gnarly motorcycle vaporized as soon as I recognized that I'd never ridden anything else quite like it. But still, the very idea of a 160-horsepower, MotoGP-inspired streetbike stripped to its core and rolling on 19-inch dirt-track tires leaves some lingering questions. Is it going to bite? Is it going to angrily chuck me down the road? Will the cops take my ATM card for bail money?

Thumbing the Tracker’s starter button does nothing to quell the remaining nerves. The crossplane-crank 998cc engine barks to life with a raucous, staccato boom reminiscent of a 427 Cobra. The engine’s unique cadence is instantly recognizable, albeit about 10 times louder than stock because it erupts through a stubby carbon-fiber Graves “silencer” that juts out beneath your right foot.

That blasting exhaust note is a stark contrast to the incredible details that Tracker builder Gregg DesJardins has crafted into his latest project. If there is one thing that ties together the five GC machines Cycle World has sampled over the years, it is DesJardins' absolute obsession with the details and how a huge part of the overall impact is the powerful combination of subtle nuances.

custom yamaha yzf r1 tracker studio side view
Gregg's Customs Yamaha YZF-R1 Tracker.Cycle World

Inspiration? "I knew about Kenny Roberts' scheduled ride on the TZ750 at the Indy Mile during last summer's MotoGP weekend and was familiar with the legendary story of when Roberts won the same race on the original bike in 1975," said DesJardins. "And my first bike was an RZ350, so I've always been into two-stroke Yamahas, and the TZ750 was the pinnacle. My idea was to get an R1 and make it into a street-legal tribute to that Miler, then show it at Indianapolis."

Like any custom, the completed bike has to convey the chosen image, so the finish of each part was carefully considered. DesJardins wanted the Tracker’s metal parts to look racer raw, so all of the titanium and aluminum fabrications were left untreated, while the fork, triple-clamps, wheels, hand controls and Graves Motorsports engine covers were clear hard-anodized by Santa Clara Plating for a “works” look.

The first major thing DesJardins attacked was the aluminum frame, stripping all unnecessary brackets and filling unused holes. Nickel plating was a must, so the frame and one of GC's signature single-sided tubular swingarms were sent to Sport Chrome for the proper treatment. But when DesJardins got the pieces back, he felt they looked "too nice" for his racebike theme, so he instantly hit the parts with a Scotch-Brite pad, much to the horror of his friends hanging out at the shop that day! But the end result was the patina he felt was appropriate.

Mounting tabs for the front fender were shaved from the stock Yamaha fork, though the mounts for the stock six-piston caliper remain on the left stanchion in a nod to streetability. Adjustable-offset A&A Racing triple-clamps are set full-forward to help the fat, 19-inch front tire clear the Ron Davis custom aluminum radiator. A flat-track-bend handlebar from Drive Systems USA bolts into A&A risers.

custom yamaha yzf r1 tracker cornering action
Gregg's Customs Yamaha YZF-R1 Tracker.Cycle World

About those wheels: DesJardins planned to fit 17-inchers, but a conversation with roadracer Eric Bostrom—who cut his teeth in dirt-track racing and took a liking to the R1 Tracker concept—convinced him otherwise. It had to have 19-inchers to look at all legit, Bostrom argued. So, forged aluminum Performance Machine dirt-track racing wheels were equipped with custom hubs, the front to accept a lone Brembo disc, the rear to fit the single-sided swingarm. Dunlop dirt-track racing rubber in the hardest-available compound is fitted front and rear.

Without a doubt, the most difficult aspect of the build and the bike’s signature piece is the fuel tank. “New bikes have tons of plastic everywhere, and I wanted to get rid of all of it,” said DesJardins. “The fuel tank has covers that blend the sides and back into the frame, and the entire front section toward the steering head where the airbox resides is plastic.”

An exposed air filter was a must because every real dirt-tracker has them hanging out in the breeze. “I decided to cut off the front of the airbox (also plastic) flush with the filter to get the effect, and then I came up with the idea of the aluminum cage to mimic the lines of the airbox cover,” said DesJardins. Metal was added to the rear of the tank, then he cut off the protrusions on the tank’s sides, forming pieces on an English wheel to fill the voids. Stock gauges drop right in the open recess in front of the air filter, making them visible from the rider’s seat without cluttering the top triple-clamp.

The front “numberplate” was fabricated from aluminum sheet but boxed, peaked and creased to add dimension. For lighting, DesJardins spun up on his lathe a cylindrical housing to fit a 2008 Suzuki GSX-R1000 projector-beam headlight. Bodywork was finished off with a First Klass Glass dirt-track tailsection and seat, to adorn the custom-fabricated titanium-tubing subframe. For a notional effort at street legality, a one-off LED taillight is hung out back. Turnsignals? Mirrors? Whatever...

custom yamaha yzf r1 tracker front section details
Gregg's Customs Yamaha YZF-R1 Tracker.Cycle World

Paint, of course, had to be special. A combination of gold metalflake and gold candy—with subtle Yamaha tuning-fork watermarks—was sprayed by Roberto Serangeli at Blue Cat in a custom riff on the traditional Roberts bumblebee scheme.

Yeah, yeah, eye candy is bitchin’. But to be truly cool, there has to be some other form of stimulus to permanently burn the entire experience into your brain. That can only come from a butt-puckering ride on the Adrenaline Express. With full liter-bike fury and a new, stripped-down dry weight of 380 pounds (minus 62 from stock!), GC’s Tracker delivers like no other: It snaps, spins, spits and wheelies with outright aggression all while making so much racket that you’re positive that someone must already have dialed 911.

Speaking of 911, when we turned the bike over to resident nutter Mark Cernicky for photo modeling, he returned more wild-eyed that normal. “This is the closest I’ve ever come to riding a ‘drift motorcycle,’” he said with a mad laugh. “It’s a mega-horsepower literbike, but with a narrow seat and high, wide bars to hang onto, allowing you to exercise the outer limits of control over those dirt-track tires. There aren’t words to describe how much fun I had riding this thing!”

That’s one reason we took photos...

With those big Dunlops squirming underneath you—the rear clawing in vain for traction on the asphalt—you can at least imagine what a handful Roberts’ big TZ must have felt like when he wrestled it around the Indy Mile. Okay, maybe not! But we can assure you that this R1 isn’t for the faint of heart. Its frenetic behavior when the throttle is stretched WFO has to be experienced to be believed. It’s simple, nasty, raw and unruly. Calling this street-tracker “cool” is the understatement of the year.

Check out more photos of the Gregg's Customs Yamaha YZF-R1 Tracker:

custom yamaha yzf r1 tracker on road action
Gregg's Customs Yamaha YZF-R1 Tracker.Cycle World
custom yamaha yzf r1 tracker straightaway action
Gregg's Customs Yamaha YZF-R1 Tracker.Cycle World
custom yamaha yzf r1 tracker studio side view
Gregg's Customs Yamaha YZF-R1 Tracker.Cycle World
custom yamaha yzf r1 tracker rear section details
Gregg's Customs Yamaha YZF-R1 Tracker.Cycle World
custom yamaha yzf r1 tracker instruments details
Gregg's Customs Yamaha YZF-R1 Tracker.Cycle World
custom yamaha yzf r1 tracker wheelie action
Gregg's Customs Yamaha YZF-R1 Tracker.Cycle World