SR Project Bike: 2007 Kawasaki ZX-10R - The Blue Streak

Project Bike

In The Normal Course Of Magazine Testing, Bikes Are put through the wringer and then returned to the manufacturer-job done, thanks for playing. Sometimes, however, we get the urge to hang on to a bike and tinker, maybe to improve some aspect of the bike we didn't like, or perhaps to test some aftermarket products. And sometimes we just want to keep a bike around because we like it so much. Case in point: this '07 Kawasaki ZX-10R. After our last year's literbike comparison test ("Literbike Lunacy," Aug. '07) we found that swapping out the Kawasaki's stock front tire made a huge difference in the bike's behavior, transforming it from a ponderous handful on the street to a neutral-steering rocketship. With that change, we didn't want to return the ZX-10R-partly because it was so much fun to ride, but mostly because the tinkering gene had kicked in. If a front tire made that much difference, what would, say, some aftermarket wheels do?

It was a golden opportunity to try Marchesini's forged aluminum wheels, and because the company has moved under the Brembo umbrella we thought we'd sample Brembo's new line of High Performance goodies at the same time. As usual the snowball effect resulted in a couple of weeks' worth of UPS deliveries and a 165-horsepower toy that reminds us of why we liked the original, '04 ZX-10R so much: Our modified Kawi is a light, fun package that is docile and playful as a kitten when puttering around but ready to pounce like a lion anytime you're willing to pull its tail.

The real impetus behind our project Kawasaki is the wheel and brake combination. Brembo's HP line includes calipers and rotors intended for the street/track rider, with performance and pricing a step down from the full-on Superbike bits. The two-piece radial-mount calipers run $1550 for the pair-still not cheap, but less than half the cost of the higher-spec, one-piece units-and the rotors cost $610 for the pair. We matched the discs and calipers with one of Brembo's RCS (Ratio Click System) master cylinders, which also falls under the HP line and costs $365. Marchesini's forged aluminum wheels-not quite as light as their magnesium counterparts but significantly sturdier and cheaper, and lighter than the stock wheels-run $2222 for the set.

There's no point in mounting up shiny new wheels with old tires, so we spooned on a set of Continental's new ContiRace Attack high-performance sport tires. The new tire is a development of the company's ContiSport Attack, using a continuous compound technology and sparser tread pattern for more grip. The Race Attack is a street/track tire that is also available in a competition version, but we chose the standard version in keeping with the ZX-10R's intentions. One feature that prompted us to pick the Continentals is that the rear tire is offered in both 190/50 and 190/55 rear sizes, the 55-series tire matching the Kawi's stock tire. Street prices for the new Contis typically run $340 per set.

Out back the Marchesini wheel called for a nonstock sprocket to fit; we sourced an aluminum sprocket ($74.95) from Driven USA, which offers sprockets and chains in practically any custom combination with a variety of colors to choose from. While we were at it we ordered a one-tooth-smaller front sprocket ($29.95); both were in stock 525 pitch so we wouldn't have to mess with the chain. Installation of the wheels and brakes included a couple of snags: The rear disc bolts needed some washers underneath to account for shallower counterboring of the wheel, and the calipers and master cylinder needed different banjo bolts from stock, which weren't included in the kit. Galfer came to the rescue here with color-matched stainless steel lines and the correct fittings for everything ($98).

Not that the ZX-10R needed more power, but we couldn't stop ourselves from ordering a KR Tuned full exhaust. The beautiful stainless steel header and carbon canisters are flawlessly constructed, and performance is top-notch. Jeremy Toye of Lee's Cycle (858/541-2080, http://www.leescycle.com) installed the pipe and created a custom Power Commander map to match. Toye pointed out that simply installing the Power Commander with a map downloaded from the internet actually reduced power and that the full benefit of the pipe was only realized with a custom map-as is the case with most installations.

Knowing how our last-year's GSX-R1000 project came alive with the addition of a timing retard eliminator that tricks the bike into thinking it's in a higher gear-and using the more aggressive mapping to match-we found a similar unit for the ZX-10R. While we were on the phone with Cal-Sportbike ordering the Heal Tech GI Pro we also arranged for a Pipercross foam air filter ($58.99). That's the limit of our ZX-10R engine modifications; why mess with excess?

The danger with most project bikes is that they often turn into a "hop-down," as we sometimes call them, and the combination of the selected parts ends up worse than stock. Nothing could be further from the truth here: Our project bike exceeds our expectations, working better in almost every aspect. Steering is light and delightfully neutral, a nice change compared with the stocker. The lighter front end helps transitions, and the ZX feels much more nimble than the few pounds saved in the front end would suggest. Certainly magnesium wheels would be a step better again, but with aluminum comes the security of knowing the wheels will survive the Department of Public Works' best attempts to bend them on the edge of a pothole.

Likewise the Brembos are a huge improvement over the already-good stock parts. Braking is one-finger powerful, although some heat is needed in the system, and response is crisp without being grabby or too progressive. The Continentals provide excellent grip and the same neutral steering as the standard (non-OEM) front Dunlop Qualifier, and wear looked better than average for a high-performance sport tire.

The ZX-10R is known for being smooth and ultrapowerful, and our modified bike has even more steam and delivers that power even smoother. The custom map gives instant throttle response at any rpm, and in concert with the smaller front sprocket and lighter front wheel it makes for a very, shall we say, happy front end. Toggling the map on the GI Pro reveals an interesting detail: While the off/on throttle is smooth on the default setting, switching to one of the other maps-fooling the ECU into thinking the bike is in fifth or sixth gear-adds a bit more power at lower rpm at the expense of the buttery throttle response. Further mapping of the Power Commander may clean that up, but in the meantime the GI Pro stays on its standard setting.

There is one flaw in our project Kawasaki: The extra power and stronger brakes exacerbate the stock bike's chassis pitch, and the bike wheelies too easily under power-even when leaned over in a corner. Fun, yes, but some suspension mods would be next on the list to better control the chassis. Still, it's the overall package that brings a grin to our faces every time we ride our potent ZX. The mix of silky throttle response, acres of usable power, neutral steering and crisp, responsive brakes gives the rider more confidence than the stock bike ever could. It's a fantastic daily rider as well, running clean and smooth in town and on the freeway. Wait, there is another flaw: Now we have to give the bike back to Kawasaki.