Mule Motorcycles Custom Yamaha YZF-R1 Jeff Allen

It’s no exaggeration to say that this Mule Motorcycles-built Yamaha custom is the bike that saved roadracing in America. It’s the machine that initially brought together Wayne Rainey, Terry Karges, and Richard Varner and spawned a series of ideas from limited-production customs in concert with Yamaha to a roadracing-based reality TV show, which ultimately all led to the formation of the new MotoAmerica roadracing series that’s taken over AMA superbike racing. Varner is the man behind this bike and the “V” in KRAVE (Kargas, Rainey, Aksland, Varner), MotoAmerica’s parent group. He also happens to be a crazed motorcycle enthusiast and, as you might guess, designed the paint scheme to celebrate the bike’s role. “Gordon McCall who puts on the Quail Motorcycle Gathering is a buddy of Wayne Rainey’s,” Varner says. “Wayne wanted to get re-involved in the motorcycle industry beyond doing appearances for Yamaha, and Gordon got us all together to discuss what could Wayne do to get back into motorcycles in a bigger way.” Rainey had seen a Yamaha XS650-based café bike Varner had done and was intrigued since he’d gotten his start on those four-stroke twins in flat-track racing. But an initial hope was to build a limited-production bike that Yamaha could somehow be involved with, due to Rainey’s long history with the company and the matter of those World Championships...

Mule Motorcycles Custom Yamaha YZF-R1 Jeff Allen

There could be no one else to build this bike but Richard Pollock, the tightly focused beam of human energy that is Mule Motorcycles. You’ve seen Mule’s work here before, and Pollock is one of the most prolific builders of custom bikes in the world. He also worked with Champions Moto, Varner’s custom-bike and apparel company. As Pollock, Varner, and Karges brainstormed on the flight back from their Monterey, California, meeting with Rainey, one of them was flipping through a magazine with a feature on Yamaha’s legendary TZ750 two-stroke roadracer. It had a black engine. It was an inline-four. The cylinders were canted forward. “The idea began to gel,” Varner says, and the YZF-R1 came into focus as the perfect choice. Sketches were ordered, direction and design was chosen, and Pollack found the donor R1, a 2004 ex-Larry Pegram backup superbike. “I got it in the shop and totally disassembled it,” he says. “We made a fixture to mount the stock frame. I didn’t want to reinvent the geometry. It took about eight months to get the basic frame laid out and tubes bent, meeting the motor mounts, clearance for the clutch, et cetera. I was designing to get the look and stance of the TZ. The essence of the bike isn’t a dumbed-down R1 but an uprated TZ750. If you built the TZ using a current motor and did all the things to upgrade it to a more current spec, this is what it would look like.” The result is a fully hand-fabricated 4130 chrome-moly twin-spar frame that echoes the TZ750 tubular-steel piece but with modern geometry and Mule’s own custom adjustable-offset triple clamps.

"I was designing to get the look and stance of the TZ. The essence of the bike isn’t a dumbed-down R1 but an uprated TZ750. If you built the TZ using a current motor and did all the things to upgrade it to a more current spec, this is what it would look like," Pollock says.

At the rear, the 6061 aluminum swingarm has the same dimensions as stock but is based on a 3-inch extrusion with tubular bracing made by custom swingarm specialists Trac Dynamics. Rainey, as you might imagine, has a few connections at places like Öhlins and Brembo. That’s where the oh-so-perfect Japanese-market conventional fork comes in, and the linkage-less shock was built from a menu of parts supplied and assembled by a factory insider. That was the end of the easy stuff. “One of the biggest challenges of the bike was packaging all the electronics and figuring out the wiring—it was a nightmare,” Pollock admits. “I built the bike, and there was just no place to put anything, so I had to work out that puzzle.” Pollock then showed me a wall-size wiring diagram he made and marked up to help make sense of the miles of wires in a modern, fuel-injected superbike. The ECU now lives under the fairing, à la TZ750, in a sweet, welded bracket on the fairing mount, and a wiring block is mounted between frame spars on the left. A lightweight carbon-fiber-shell lithium-ion battery from Lithionics is mounted in the tailsection.

Mule Motorcycles Custom Yamaha YZF-R1 Jeff Allen

Which brings up bodywork. Hanging on that chrome-moly frame is genuine TZ750 bodywork that has been heavily reworked. It’s been widened and massaged to fit the larger scale of the new machine while maintaining the stance that made the TZ750 famous. This might be one of the coolest tailsections of all time. The rear subframe is constructed using heim joints, allowing for up-and-down and fore-and-aft adjustment. While Pollock rates the wiring and other packaging as the biggest problem of the build, the Rob North-fabricated aluminum fuel tank and airbox, which are integrally designed, rate pretty highly: “We have at least a month in the airbox,” Pollock says. “I tell everybody we should have built an airbox and put a frame around it.” Rims are 18-inch Harley-Davidson XLCR, both rears, widened by Kosman to 2.75 inches at the front and 4.5 inches in back. Mule machines adaptors for brakes, sprockets, and stock R1 wheel bearings. Brembo supplied the radial master cylinder and redline monoblock calipers. Kosman then turned Pollock on to a company called Ultra Lite Brakes, which cuts discs from titanium and ceramic coats it to work as brake material. A single front bare rotor costs $1,100 but is 30-percent lighter than the steel equivalent. “They use them on NASCAR racers, but they aren’t done for bikes much because of the cost,” Pollock says. “We made the inner carrier and used Brembo buttons. They work great and seem to improve with use.”

“One of the biggest challenges of the bike was packaging all the electronics and figuring out the wiring—it was a nightmare,” Pollock admits.

Mid-build, Pollock took the bike to Rainey’s house for a star-studded party during the July 2013 MotoGP weekend. There, the bike got an incredibly experienced and knowledgeable audience: “Kenny Roberts was there; Masahiko Nakajima, head of Yamaha Racing; Chuck Aksland who worked for Roberts for years; and this guy named Dirk Debus, who works with all the data that all the teams collect,” Pollock relates. “I wanted feedback from guys who had been around the block. Kenny looked at it and he says, ‘Holy crap. You’ve got a lot of work into this thing.’ He understood the effort I put into it. Nakajima was really fascinated and crawled around looking at it. “If I was wrong about something, I wanted to know.” The results of the MotoGP inspection were a relief. “Debus suggested increasing the size of the airbox intake scoops and to relocate some electrical components,” he says. “Roberts said it needed a wider front rim for a better tire footprint, so we got a new rim made. Nobody had a big criticism, but I’m not sure they knew what to think! Who would do this kind of combo, right?” With that, Pollock forged ahead to the finish. The end result weighs less than most modern superbikes, makes 180 hp at the rear wheel, and will ultimately be set up with lights. What could be cooler? Well, maybe the planned TZ750-inspired R1 street tracker built using a similar for­mula. If these bikes are any indication of the enthusiasm of the people behind Moto­America, racing is in good hands.

Mule Motorcycles Custom Yamaha YZF-R1 Jeff Allen

Mule Motorcycles Custom Yamaha YZF-R1 Jeff Allen

Mule Motorcycles Custom Yamaha YZF-R1 Jeff Allen