There’s a lot to be said for a good old-fashioned muscle bike. And in the 1980s, the Kawasaki GPZ900R was the benchmark. It didn’t have any of the nanny state electronics we’re used to today, but the raucous, liquid-cooled DOHC four punched out 113 solid horses—and propelled the GPZ to 150 mph or more.
No wonder the producers of the original Top Gun movie selected a GPZ to star alongside Tom Cruise, who knows how to handle a bike.
We’ve noticed an uptick in custom GPZs lately, going right back to ICON’s ‘Old Ghost’ of six years ago. AC Sanctuary have built some brilliant restomods too, but this GPZ900R from Berlin has a completely different vibe. It’s all business—raw and stripped back
It comes from the increasingly prolific German firefighter Chris Scholtka, who runs Motocrew in his spare time. “I started the build a year and a half ago,” Chris tells us. “It should have been a low budget bike, but it escalated quickly…”
Chris is a Kawasaki fan and his whole family bleeds green. “I have a 1998 Ninja 600 in original condition, and a KX250F. My dad rides a Ninja 1000SX and a Ninja 900, and my girlfriend a Z550.
“The GPZ900R is a good bike for customization because of the bolt-on rear frame. In Germany, we can’t weld around the main frame—but on a GPZ the rear and main frame are in two separate pieces, so you can build a new rear frame. And the engine is powerful!”
The inline-four on this 1984 machine was in brilliant condition, but the hardware around it wasn’t.
So Chris started by fettling the engine, and getting it as perfect as it could be, with a light refresh. He’s added a Dynojet kit and a 4-into-1 exhaust from the German company Speed Products. With a stubby SC Project muffler attached too, Chris reckons the output is now around 130 hp.
“I will take the bike to a dyno to get a good setup, but the power (in combination with the roughly 20 kg weight reduction) is really nice for a bike of this age.” To get that power on tap as fast as possible, Chris has also fitted a Ducati quick-action throttle.
Chris’ next mod on the 1984-spec Ninja was the tank. “The original is too big and unshapely for my taste, so I picked up a Honda Bol d’Or [CB750F] tank, with a pop-up gas cap for a cool old school touch.”
Chris has ditched the somewhat dated and heavy plastic bodywork, and installed a low-key, café racer style bikini fairing, welding up a set of brackets to make it fit.
He’s also refreshed the original forks and lowered them a couple of inches for a more aggressive stance. “I could have swapped in a USD fork, but that would have blasted away the ‘low budget’ concept.”
Chris is not sure what the wheels are, because the previous owner installed non-standard mags. “They’re from a newer GPZ version, I think,” he says. The rubber is ZR-rated Shinko: “I ride with a 130/60-16 SR880 at front, and a 170/60-18 R006 RR at the rear.” He’s got the relevant certificates of permission from Shinko for the German TÜV authorities.
The subframe is a minimalist bolt-on loop, which Chris made himself—along with the flush-fitting seat. A friend upholstered it in Alcantara, with a diamond stitch pattern.
“The goal was to get a classic café racer back end—one that fits with the wide rear tire,” says Chris. “For better street road holding, I’ve used a Scrambler Ducati rear shock taken from an earlier Ducati build. I can say I recycle my parts…”
It’s not worth taking a chance on electrics that are almost four decades old, so Chris has fitted a full suite of Motogadget accessories—including turn signals, the speedo, and an RFID ignition system, all wired into an m.unit control box.
While looking for a pop of color to offset the black paint on the GPZ, Chris heard about Hookie’s new ‘Frozen’ translucent silicon grips.
“I got the new grips to test before the release, so I decided to put the Hookie logo on the tank, to say thanks for the support. Hookie Co. have been a big inspiration for me from the beginning, and to get exclusive products from a company I look up to is a big honor.”
Chris wasn’t finished there, though. He also located a 1983 Kawasaki Z550, and spent a month modding it for his girlfriend’s 27th birthday. It’s simple and effective—a new seat loop, headlight arrangement and tires, plus a general refresh.
The perfect match for the big brother GPZ900R—but probably a little less intimidating to ride.