Muzzy SB 750 Raptor

If you're a typical hot-blooded road-race fan, you've probably fantasized about shredding your usual Sunday-morning backroad aboard a championship-caliber Superbike. Taking to the street on such a bike would inspire you to dive deeper into corners and roll back into the throttle sooner than you ever thought possible. Its nimble handling and highspeed stability would impart a sense of being glued to the road that would entice insane lean angles, while its awesome power would produce arm-stretching wheelies off corners. You also could imagine the attention such a machine would draw from the benchracing boys at the local sportbike haunt.

Ahhh...a vivid imagination certainly can make your pulse race.

Well, snap out of it, pal, and get down to your local Kawasaki dealer-your dream bike awaits. The Muzzy SB-750 Raptor, essentially a turnkey, street-legal Kawasaki ZX-7R Superbike, is everything we've just described. This limited-edition, $18,000, for-real repli-racer is the work of Rob Muzzy, one of the premier tuners of our time. Since taking over Kawasaki's factory roadrace program in 1989, Muzzy has compiled an impressive resume that includes one World Superbike Championship, three AMA Superbike Championships and three AMA 750cc Supersport crowns, all won on ZX-7s.

Says Muzzy, "The Raptor brings the 'tuner-car' concept to the motorcycle enthusiast. In the tradition of the Shelby Cobra, the Callaway Camaro and the Saleen Mustang, the Raptor takes a stock Kawasaki ZX-7R and refines it to meet the desires of the most sophisticated street rider, collector or racer." The fact that Muzzy has visited Saleen to examine that operation underscores the parallel.

Muzzy has no intention of offering Raptor kits; instead, the motorcycles will be sold complete, assembled at Muzzy's shop (called "Muzzys," without an apostrophe) in Bend,

Oregon. To purchase one, a customer goes to a participating Kawasaki dealer and buys a ZX-7R in the usual manner. The dealer then calls Muzzys to place an order for a Raptor, and either ships the new ZX-7R from his shop's inventory or has one drop-shipped from a Kawasaki warehouse. After Muzzys performs its magic, the bike is shipped back to the dealer for delivery to the customer. The customer is entitled to keep the stock parts removed during the transformation, but must notify Muzzys of his desire to do so, and must pay the shipping charges incurred in returning them.

Raptor conversions begin with complete disassembly of the original ZX-7R. The stock frame and swingarm are then painted black before the chassis is carefully reassembled in blueprint fashion. If desired, an Italian-made RAM cast-magnesium, single-sided swingarm like our testbike's can be added at this time, a $3749 option. Up front, a handsome, black-anodized, billet-aluminum, offset-adjustable triple-clamp carries the standard Kayaba cartridge fork, which is recalibrated with spring and damping rates derived from Muzzys' 750cc Supersport program. Next, an ©hlins piggyback shock with a remote hydraulic spring-preload adjuster is installed, and the linkage is replaced with a less-progressive setup that eliminates the stacker's excessive free sag and provides improved bump compliance and chassis control.

The gold-anodized Marchesini magnesium wheels (17 x 3.5 up front, 17 x 6.0 out back) are the same as those used on the Muzzy Kawasaki Superbikes, and are shod with ultra^ grippy, race-compound Dunlop D207 radials. The upgraded brakes consist of dual full-floating, 12.8-inch Braking rotors in front and a single 10.8-inch rotor in the rear. Muzzys' own braided lines run to the standard Tokico six-piston front calipers (milled for cosmetic purposes), while a compact Brembo two-piston rear caliper is employed. The stock master cylinders are retained at both ends.

Muzzys has succeeded in boosting the Raptor's engine performance to well within the realm of the best Open-class sportbikes. Impressively, this was achieved without disturbing the engine's lower end, nor increasing the cylinder bore.

Internal mods consist of forged-alloy pistons that bump compression to 13.2:1, plus racing camshafts. The cylinder head receives a special racing valve job, but no porting. The standard 38mm Keihin CV carburetors are replaced by a bank of 41mm Keihin flat-slides enclosed within a carbon-fiber airbox similar to those included in Kawasaki's Superbike race kits. An all-titanium 4-into-l exhaust system with a carbon-fiber muffler caps off the package.

Our dyno runs revealed a definite enhancement in peak power, the Raptor's 125 rear-wheel horsepower at 12,500 rpm well above a stock ZX-7R's 105 bhp at 11,000 run on the same dyno. Moreover, the Raptor's power curve is quite linear, offering an ample spread throughout the rev range. Below 9500 rpm, however, output falls shy of the stock ZX-7R's, which is not surprising given the Raptor's racing influence.

A stock ZX-7R is no slouch in the top-speed arena, having posted a 166-mph run on the CW radar gun during prior testing. The SB-750 is even faster, recording a 173-mph pass despite topping out 1000 rpm short of its peak power output. Muzzy speculates that adding one tooth to the rear sprocket (thus lowering final gearing back to stock) would allow the SB to get closer to its 12,500-rpm redline, picking up a couple of mph in the process.

Muzzy shaped the Raptor's fairing from clay with his own hands. But while creating a distinctive look for the bike was important, he also sought to improve the ram-air inlet and reduce overall frontal area-thus the low-cut Targa windscreen, which contributes to the aerodynamic cause while permitting a clean, undistorted view from behind the bubble. The Raptor wanders a bit while running flat-out, but its straight-line stability surpasses that of the Honda CBR1100XX and Kawasaki ZX-11, the only production bikes we've run past 170 mph.

Circumstances didn't allow us to test the Raptor at our usual dragstrip venue, Carlsbad Raceway, so quarter-mile runs were performed on Buttonwillow Raceway's back straight instead. Although B-willow sits only 250 feet above sea level, its location in the central California valley made for less-than-optimum (read: hot) conditions in mid-July. We were disappointed in the Raptor's 10.70-second/130.94-mph quarter-mile pass until we made some comparative runs with a stock ZX-7R. Doing so proved enlightening as the stocker's best run of 11.05/127 was notably slower than the 10.77/129 it had posted in the cool Carlsbad air when tested last year. It's safe to surmise that the Raptor would shave off two- or three-tenths of a second given similar conditions.

With straight-line testing out of the way, we proceeded to lap Buttonwillow's 1.8-mile West Loop road course, which offers a variety of fast and slow corners, and places a premium on brakes. On the track, the Raptor truly feels like a racebike, due to its firm (yet compliant) ride that minimizes fore/aft pitching. Feedback through the chassis is superb, with the thin rubber seat pad literally enhancing your seat-of-the-pants feel for what's happening between the tires and the road. Kawasaki's latest ZX-7R is renowned more for its stability than its agility, but the Raptor flicks into corners quickly. Furthermore, it displayed a startling lightness during side-to-side transitions, such as those encountered in the West Loop's fast, fourth-gear esses.

The Raptor's more nimble handling results from a number of changes. First, the wheelbase measures 1.3 inches less than stock. Second, rear ride height was increased for an effectively steeper 24 degrees of rake, while a 4mm reduction in triple-clamp offset maintained sufficient trail for excellent stability. Third, the magnesium wheels not only offer a substantial reduction in unsprung weight for improved suspension response, but also less gyroscopic inertia for lighter steering.

All these changes work together nicely when the bike is ridden hard, equating to ultra-crisp handling matched by equally crisp throttle response. The Raptor's bulletproof brakes, seemingly limitless cornering clearance and eye-popping acceleration add up to one of the most exhilarating racetrack rides ever offered for sale to the buying public.

How well the package works on the street, however, depends largely on the pain threshold of the individual sitting in the saddle-and a firm saddle it is, capable of wearing the ol' bum thin during even the shortest highway hop. But once you point the Raptor down a twisty road, the physical movements entailed in sport riding get your blood flowing, and your mind off any comfort concerns.

Riding the Raptor on the road calls for re-schooling your right wrist. While CV carburetors tolerate a ham-fisted throttle hand, flat-slides require skilled restraint. Rolling on the throttle smoothly results in crisp, immediate response, but dialing in more than half-throttle before the tach needle passes 6000 rpm results in a severe stumble, even in low gear. The latter scenario causes the sparkplugs to load up, resulting in a high-rpm misfire. Winding the rev counter to 8500 rpm or beyond allows the throttle to be snapped wide-open without protest, under any load, in any gear.

In fairness, we must point out that the bike we tested is the original prototype developed by Muzzy and his star rider Doug Chandler. Production models may differ somewhat.

"I'm sure it will be a learning process," confirms Muzzy. "We're obviously a very small company, and for all practical purposes the bikes are hand-built. There probably will be some changes as we go along that will be reactions to problems or customer feedback."

This comes as good news for every hot-blooded sport rider blessed with an active imagination. If it's a street-bound racetrack refugee that fuels your fantasies, then Rob Muzzy is the dream weaver. O

Specs

liquid-cooled, four-stroke inline-Four

Bore x Stroke 73.0 x 44.7mm

Valve train dohc, four valves per cylinder, shim adjustment

748cc

Compression ratio_13.2:1

Carburetion (4) 41 mm Keihin PERFORMANCE

Front suspension: Manufacturer KYB Tube diameter 43mm Claimed wheel travel 4.7 in. Adjustments compression and rebound damping,

Rear suspension: Manufacturer Öhlins Type single shock Claimed wheel travel 5.1 in. Adjustments compression and rebound damping, spring preload, _ride height

Tires: 120/70ZR17 Dunlop D207F 180/55ZR17

Seat height 32.3 in.

Fuel capacity 4.8 gal.

Source Cycle World 1997