From Racing Dreams to Street Thrills: Kawasaki ZEPHYR750 Custom by POWER BUILDER

• ZEPHYR750

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POWER BUILDER's ZEPHYR750

"I was originally searching for an air-cooled bike to ride with my friends and came across a Kawasaki Zephyr750. I purchased it from an auction, and it was in decent condition. At the time, I was also participating in amateur racing with a VF, but finding parts for VFs was challenging. I was torn between continuing to invest money in the VF or switching to the Zephyr. I heard about a skilled tuner near Tsukuba Circuit, so I decided to visit him with hopes of receiving assistance, and I did. When I met him, I requested his help with the Zephyr," explained the bike owner. The tuner happened to be a member of POWER BUILDER, who had previously worked on the bike that became the first in history to break the 57-second mark at the TOT in the fall of 2007 (a GPZ900R in the highest Hercules class).

"First, I had it overhauled, and it became fast (laughs). He suggested, 'You should also upgrade the brakes,' but initially I left them unchanged. However, when I rode the bike at Tsukuba, I couldn't stop at the first corner. That's when I decided to invest in the chassis as well. I wanted the front fork to have an adjustable mechanism, so I extended and installed the ZX-9R fork. The wheels were also switched to 9R wheels, and the brakes were upgraded. The engine was upgraded to 850cc. POWER BUILDER was in the process of building an 850cc version of the Zephyr 750, and they experimented with various modifications on this bike, which eventually took shape. The engine underwent multiple modifications, resulting in impressive performance." This Zephyr 750 went on to win the TOT ZERO-1 class in November 2011. Afterward, the bike was equipped with safety parts and underwent some changes to make it street-legal. "The original idea was to use the bike for both street riding and racing, but if I used it on the street, the mileage would increase, leading to more frequent overhauls and quicker tire wear. After winning the championship, I planned to retire this bike from the racing scene and try a different bike in the next class. So, I decided to use it on the street and then race in the Monster class with the Katana," continues the owner. Regarding the ride quality of the street-spec Zephyr 750 the owner was a bit nervous when starting off in town, with many stop-and-go situations. However, other than that, it performs as well as on the track. Overall, the Zephyr 750 is versatile and provides a lot of enjoyment.

Handle

The low handlebar is produced by POWER BUILDER, while the top bridge is manufactured by Technical Works. The meter case resembles the stock Zephyr 750, but it features an integrated active multimeter in the left case, digitally displaying speed and other data.

Bodyworks

The black and white competition stripes, on top of a deep metallic orange color, are expertly painted in-house and positioned at the front and rear center of the body.

The double-type seat has been reupholstered to improve the hold and provide a high-quality feel. Grab bars are also equipped just like the stock Zephyr 750.

Engine

The engine remains in the same configuration as it was during its racing days, featuring the twin-plug head and Cosworth pistons for 850cc.

Intake & Exhaust

The TMR carburetor is a carryover feature from its racing days. The aluminum spigot connecting to the engine side mount is securely attached using a Z mount.

The exhaust system, previously created by Nojima Engineering for racing, is now replaced with a POWER BUILDER megaphone exhaust system.

Chassis

The simply designed step kit is manufactured by Battle Factory. The tips are crafted from Duracon (race compliant) and have a knurled texture on the bar itself.

A TOT (Taste of Tsukuba) vehicle inspection approval sticker is affixed to the front right side of the frame. The owner humorously remarks, "It looks like a seasoned veteran with a medal hanging from its chest."

The ZX-9R forks were extended to incorporate an adjustable mechanism at the front. The brakes consist of a combination of Brembo 4P calipers and Sunstar discs.

The swingarm is an aluminum square produced by Technical Works after the bike became street-legal. Ohlins rear shocks were chosen for the suspension. The front and rear wheels were replaced with ZX-9Rs, transitioning from the Zephyr 750's 3.00-17/4.00-17 size to 3.50-17/5.50-17 size. The tires selected are Pirelli Diablo Rosso in sizes 120/70 and 180/55.

Gallery

Specifications

Part	Details
Engine	JB-POWER COSWORTH 70.5mm Piston
Carb / Intake	MIKUNI TMR Φ36 Carburetor
Exhaust	POWER BUILDER Megaphone Exhaust
Frame	TECHNICAL WORKS Original Aluminium Swingarm
Brake	NISSIN Radial Brake Master Cylinder BREMBO Axial 4P Caliper SUNSTAR Premium Racing Front Brake Disc BREMBO 2P Caliper GALFER Wave Rear Disc Rotor
Suspension	OHLINS Grand Twin Rear Shocks
Steps	BATTLE FACTORY Rearsets Holder Set BATTLE FACTORY Footpeg BATTLE FACTORY Shift Pedal/Brake Pedal
Drive System	REGINA 530ZRT Drive Chain SUNSTAR RK-410 Rear Sprocket
Handle / Steering	POWER BUILDER Original Handlebar TECHNICAL WORKS Top Bridge

About POWER BUILDER

"POWER BUILDER" is a winning tuner in the Taste of Tsukuba, Japan's premier Sunday race for steel-frame bikes from the 80s and 90s. "Power Builder" is a tuner who always wins the Taste of Tsukuba, the most prestigious Sunday race in Japan, where the best bikes from the 80s and 90s compete. Power Builder" is not a restoration company, but rather a company that creates power, a company that is thoroughly committed to creating products that live up to its name.

POWER BUILDER brand page

Original Source of this Article

Heritage & Legends