A Superbike Past, Improved

Admin · March 2, 2021

Here are two of Evan Grosswirth’s rides, one built in France and one built in Van Nuys, California. As a kid, Grosswirth was folding sheet metal and hanging on the fence watching roadraces. (Evan Grosswirth/)

In 1979, 23-year-old Evan Grosswirth rode his 1978 Kawasaki KZ1000 to Loudon, New Hampshire, and was blown away by what he saw: roadracing. He knew he had to try it. By 1981 he had been hired by Lockheed Martin in Southern California and entered in his first AFM roadrace at Riverside International Raceway.

Grosswirth (805) leading Bernd Koegler at Riverside during an AFM race in 1981. As fun and fast as this racebike felt, it’s nothing compared to what Hypercycle built 40 years later. (Evan Grosswirth /)

“I had stopped in Racecrafters (a legendary SoCal performance shop) for some parts and they pointed me to Minoru Matsuzawa at Escargot racing,” Evan recalls. “Matsu helped me prep my bike for this first race, made me a pipe and rearsets. At Riverside I pitted next to HyperCycle’s Carry Andrew, who helped me a lot that first weekend—a few races later he even loaned me a pair of Fox piggyback shocks.”

Evan had some podium finishes in AFM Open classes and then life took him out of California and away from bikes; his KZ was sold and then parted out. But what Evan took with him was the incredible time he had on the Kawasaki—the fun of racing battles and being in the same race as factory riders like Lawson and Cooley. “It was a special time, that whole era of club racing,” Evan remembers. “You’d be on the same grid with AMA guys, all in vans. I really enjoyed it, had some great times.”

Who Is That Guy?

Twelve years ago Evan found himself back in Southern California and back on a bike. “I was at the Rock Store and there was a guy in a Kawasaki-green jacket who looked familiar. We started talking and it was Carry Andrew. We talked about the old days, the KZs and the racing. I’d see Carry here and there over the next few years.”

Andrew’s company, HyperCycle, never stopped building KZs, even when Andrew was crew-chiefing and tuning in the modern AMA/MotoAmerica paddock. Evan’s fond memories and Andrew’s extensive knowledge finally got these two to the drawing board. The plan: a no-holds-barred KZ1000 for the street.

Pictures Take Over the Story:

Some projects start with a crash, this one began with a low-miles 1979 LTD. The KZ and LTD share the same frame; the cruiser gets its stance due to different wheel sizes than the KZ. (Evan Grosswirth/)
The bare frame was strategically gusseted by Jerry Burac, based on what racers learned back in the day, and in the decades since. The frame-gusset kit and upgraded engine mounts come in a kit from Andrew’s longtime supplier, JB Racing. (Evan Grosswirth/)
A huge joy of project bikes is updating pieces, and Andrew uses a lot of JB Racing parts. “JB makes the high-end parts I like to use for bikes like this,” the builder told us. Jyo Bito (the JB of JB Racing) is ex-Yoshimura and American Honda racing. The 41mm Kayaba forks are built for JB Racing and are fully adjustable; a front Brembo master cylinder squeezes AP Lockheed calipers. The brake kit, triple clamps, and wheels are JB Racing too. (Evan Grosswirth/)
The frame went from black to gray powdercoat, with a clear over the top, to match the beauty of the JB Racing swingarm and Öhlins shocks. The black Öhlins were made for Harley-Davidson applications but Andrew has them built to specs suitable to the mid-400-pound KZ. Burac fabbed the lay-down shock mounts. The 18-inch JB Racing wheels off Andrew’s AHRMA-winning KZ were bolted on. (Evan Grosswirth/)
Well before the frame was powdercoated gray, Andrew test-fitted the engine and JB Racing sand-bent titanium pipe. Don’t be misled by the stock-appearing engine cases—this KZ displaces 1,105cc with JE pistons coated by Millennium Technologies, with HyperCycle cams and springs opening stock valves. The stock roller crank was trued and welded by Falicon, and this KZ wears one of the last cylinder heads that the late Mitsu Kaneda ported to specs that HyperCycle utilizes. The stock shim-over-bucket system was replaced with a shim-under-bucket kit to keep shims from being spit out. APE provided the shim-under-bucket kit, the valve-spring retainers, and cam-chain tensioner. Andrew claims 125 hp from this streetable build. (Evan Grosswirth/)
Historic colors: Grosswirth went with a reversed version of Wes Cooley’s Yoshimura paint scheme and found Bill Key of Vintage Restoration Painting in Oxnard, California, to do the work. “I’d heard great things about Bill, lots of recommendations, and his work blew me away.” The brand-new aluminum KZ tank came from <b>z1parts.net</b>, and Grosswirth also found pieces through <b>z1enterprises.com</b>. For all you KZ restorers out there, HyperCycle has carbon fiber KZ MKII (1979 and 1980) fuel tanks in the works, plus MKII bodywork, including the seat base to be legal for AHRMA. (Evan Grosswirth/)
Carry Andrew doing what he does best, and what’s he done since the 1970s: build exquisite street- and racebikes. At this point in the build, Andrew is pre-fitting components and bodywork to determine what frame tabs to add or delete. Grosswirth was very hands-on in this project, doing the LTD teardown, maintenance tasks, and much of the removal and replacement of parts. (Evan Grosswirth/)
Grosswirth flies 600-mph corporate jets for a living (Dassault Falcon 900) and brought an all-in attitude to the KZ. For readers looking to do a lifetime-keeper project like this, Grosswirth advises: “Have a plan on exactly what you want to do. Take your time, don’t skimp on it, think it through. I never wanted to look back and say, ‘I shoulda done this.’ The no-look-back thing was big for me.” (Evan Grosswirth/)
Final fitment is to the point of installing the Dynatek 2000 electronic ignition. There’s a Barnett clutch in there, and Tom Malaska of Malaska Motorsports did the transmission, as he’s done since the ’70s. Andrew built this engine to spin to 11,500 rpm, just like the Superbikes did on the high banks of Daytona in the championship days of Pridmore, Cooley, and Lawson. Andrew was there then too with a best finish of fifth (at Laguna Seca in 1980), and currently races at the front of AHRMA on the same KZ Superbike he raced in AMA. Grosswirth wanted the real deal. (Evan Grosswirth/)
JB Racing has these 35mm Keihin flat-slide carburetors modified per its specifications, and Grosswirth is smart enough to run K&N air cleaners to protect the engine. Those are a beefy JB Racing oil cooler and JB Racing footpegs. (Evan Grosswirth/)
Grosswirth did not make the common mistake of increasing engine power and ignoring braking power. This clean full-floating JB Racing setup provides modern power and feel, and Andrew spooned on AHRMA favorites, a set of 18-inch Continental Road Attack tires. (Evan Grosswirth/)
If you’ve messed around with cable-driven tachometers and speedometers, you know why Grosswirth opted for this Koso electronic tach and digital-readout speedo. “It comes with pickup magnets you adjust, plus some settings, to get the speedometer right,” Grosswirth reports. “After a little fiddling, I got it to within 1 mph of my local Highway Patrol’s certified speedometer.” (Evan Grosswirth/)
There are many ways to get to breakfast, but few as satisfying as on a bike you imagined and constructed. Grosswirth’s bike sits at California’s Rock Store: a 1978 profile with improved performance. “It’s so light and responsive, just a joy to ride,” the pilot tells us. “And I also enjoy sharing something like this with other people.” Grosswirth turns 65 in May and relives his AFM racing youth every time this KZ fires. (Evan Grosswirth/)
Nothing better than a Sunday in the canyons, especially on a unique motorcycle. Andrew and Grosswirth combined to build a bike we hope motivates all dreamers. The parts are available to travel back in time, but with significantly more performance and reliability. John Ethel of Jett Tuning helped Grosswirth set up the Kayaba fork and Öhlins shocks, just another example of accomplished AMA tuners ready and waiting to help with all our projects. (Evan Grosswirth/)
The meaning behind Evan’s “New York steak” license plate? During development of Kawasaki’s 1973 Z1 (900cc)—at a time when Kawasaki was taking direct aim at industry-leader Honda—the Japanese asked, “What is the best thing on an American menu?” “New York steak,” the American Kawasaki management told them, and that became the preproduction code name for the Z1, which became the KZ1000. (Evan Grosswirth/)
From here… (Evan Grosswirth/)
…to here. Imagine, budget, build. Money spent on project bikes pays lifelong dividends. What price joy? More than 2,500 miles of smiles so far for Evan Grosswirth and his exquisite HyperCycle KZ1000. (Evan Grosswirth/)