Zx-7 Upgrade

ZX-7 UPGRADE

CW PROJECT

A LITTLE HELP FOR LAST YEAR'S MODEL

MATTHEW MILES

KIRK WILLIS

PLANNED OBSOLESCENCE IS NOT necessarily an evil thing. Take Kawasaki's ZX-7 series, for instance. Sure, the 1993 model you’ve just read about is a wonderful piece, obviously better than the 1990-’92 versions, but with a few well-chosen upgrades those models are still desirable. Even better, since the older bikes’ stock has just gone down in the eyes of enthusiasts, a bargain hunter should be able to find some great prices on used ZX-7s or work himself a sweet deal at any dealership with leftover models.

To illustrate the bike’s potential, Cycle World's 1992 ZX-7 testbike was given an aftermarket makeover. Upgrading the overly stiff suspension was the first step, and it’s a relatively inexpensive one. Newport Welding Services, a British fabrication firm, supplied a new rear-suspension link.

By changing the leverage ratio, NWS’s link “softens” the suspension by a claimed 9.5 percent. Fitting the castaluminum link is simple, though the exhaust system has to be loosened and the muffler removed. Functionally, the link works as claimed, but it doesn’t altogether compensate for the stock shock, which, like the fork, is needlessly harsh in action.

With a request for less compression damping and a lighter shock spring, we sent the shock and fork to Pettersson Pro Suspension. Stig Pettersson revalved the fork, refitted the stock springs and set the oil level at 6.3 inches using Spectro 7.5-weight fork oil. Besides revalving the shock, he also exchanged the standard 16-pound shock spring for a 14-pound spring from Fox Racing. As specified by Pettersson, the shock’s spring preload was set to give 1.25 inches of sack. Compared to the stock set-up, the reworked suspension is noticeably improved. Both ends are more compliant over small bumps, and most of the aforementioned harshness has been eradicated.

Improved braking performance was our next goal. Although the ZX-7’s brakes are impressive, there is room for improvement. Our first step was to replace the rubber brake lines with Fren-Tubo Kevlar hoses from Indigo Sports. Fightweight, with anodized aluminum fittings, the Italian-made hoses all but eliminate line expansion, improve feel and fit perfectly. EBC pads and AP Fockheed 600 fluid completed the brake modifications. With these changes, braking is first-rate, both on the street and the racetrack.

Because the original-equipment Dunlop Sportmax radiais were wearing thin, we upgraded to Dunlop’s GP-compound Sportmax radiais (now standard on the ’93 ZX-7s). While the GP front differs from its stock counterpart in compound and price only, the rear Sportmax GP has a slightly different construction and profile. We were very pleased with the GPs and their neutral steering characteristics, excellent grip and impressive durability. If cost were a factor, though, we wouldn’t hesitate to refit the lessexpensive standard Sportmaxes.

During testing, our ZX-7 blew a fuse and overheated. Fortunately, damage was limited to a slightly distorted radiator fan. Instead of buying the complete fan assembly for $253 (Kawasaki doesn’t sell just the fan), we ordered a replacement fan from Hiltsystems in Wichita, Kansas, for $19. According to Hiltsystems, the stock fan’s plastic blades can distort due to their proximity to the exhaust, then stick in the fan shroud, blowing the fan-motor fuse. Hiltsystems’ aluminum replacement fan has two more blades than stock, a different blade pitch and, according to the manufacturer, moves more air and will not distort under extreme heat. Installation is straightforward, but the bodywork and radiator must be removed to access the fan assembly.

Turning our attention to details, we ordered Indigo Sports’ rearset footpegs. Designed for the serious sport rider and racer, the rearsets are machined from billet aluminum and located an inch higher and V4 of an inch farther back than stock. Although we liked their stylish appearance, we found the nonfolding pegs a bit high for street use, especially for riders over 6 feet tall. At the racetrack, however, the additional ground clearance was appreciated.

We also added Indigo Sports’ carbon-fiber frame guards. Exotic looking, the lightweight guards are designed to protect the Kawasaki’s aluminum frame beams in the event of a crash. Further improving our project bike’s appearance, we fitted a Poggipolini fairing-bolt kit. Gold anodized, the aluminum bolts are claimed to be 67 percent lighter than stock and corrosion resistant.

Our testbike’s molded plastic windscreen was very wavy, resulting in distorted full-tuck vision. Targa’s replacement windscreens are optically correct, pre-drilled for easy installation and manufactured in a variety of colors. For improved wind protection, we fitted the larger of the two sizes offered. We also ordered one of Targa’s slip-on fiberglass seat cowls. Designed for street use, the cowl provides solo looks, but slides off for twoup riding. Although the fit wasn’t quite perfect, the paint match was excellent.

Our final cosmetic task was to clean up our ZX-7s tailsection. Competition Werkes’ fender-eliminator kit bolts into place in less than an hour and completely disposes of the rear fender.

On a negative note, the edges of the stainlesssteel fender pan are very sharp and must be filed smooth prior to installation. Also, the kit makes no considerations for relocating the factory tool pouch. Visually, though, the kit is a dramatic improvement over stock.

We didn’t touch our ZX-7’s engine. At 90 horsepower, it gives away 14 ponies to the 1993 model, and is the only area in which our project bike is at a serious disadvantage to the new 7.

Additional power is available, though, via compo-

nents from the limited-edition ZX-7R, which last year churned out some 106 horsepower. According to Tom Houseworth of Houseworth Power Services in Santa Ana, California (714/554-1486), all that is required are 7R camshafts, high-compression pistons, rings and gaskets. Cost for the transplant, which includes parts, a valve job, camshaft degreeing and labor, is $1400; gains of 19 horsepower have been recorded.

We decided to keep the Houseworth hop-up as a future option, and ride the project ZX-7 as is. From a functional as well as a visual perspective, the bike is already a success. Its upgraded suspension, stickier tires and strong brakes offer improved performance over stock, and cosmetically, the bike is as pleasing to look at as it is to ride, proving there’s lots of life in old-style ZX-7s.

3UPPLIERS

Competition Werkes

P.0. Box 5233 Roseburg, OR 97470 503/673-6059 or 800/736-2114 Fender-eliminator kit: $90

EBC Brakes

12860 Bradley Avenue Sylmar, CA 91342 818/362-5534 Brake pads: $24 per caliper

Dunlop Tire Corporation

P.0. Box 1109 Buffalo, NY 14240-1109 800/548-4714

Sportmax GP 120/70-17: $144 Sportmax GP 180/55-17: $193

Essex Parts Service

2350 Pendley Industrial Park Boulevard

Cumming, GA 30130 706/889-4096

AP Lockheed 600 brake fluid: $20

Hiltsystems

1133 S. Rock Road #3-273

Wichita, KS 67207 316/788-3558

Replacement radiator fan: $19

Indigo Sports

12405 Slauson Avenue Unit J

Whittier, CA 90606 310/945-8149 Racing exhaust: $795 Fren-Tubo Kevlar brake lines: $148 Rearsets: $150

Carbon-fiber frame guards: $160 Poggipolini fairing-bolt kit: $88

Pettersson Pro Suspension

817 Lakeview Avenue Unit B

Placentia, CA 92670 714/970-2423 Revalve fork: $95 Revalve shock: $130 Fox Racing shock spring: $80

Newport Welding Service

Unit 4, Conbar House, Mead Lane Hertford, England SG13 7AP (44) 099 250 1285 Rear-suspension linkage: $160

Targa Accessories

21 Journey Aliso Viejo, CA 92656 714/362-2505 Windscreen: $40 Seat cowl: $93