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Kawasaki KZ1000S1 Resto Replica – Chasing Eddie

Kawasaki kz1000S1 static left side profile

At first he thought he’d built the bike of his dreams, then realized he’d fallen short of the legendary KZ1000S1. He’d try again.

Chasing After Eddie

Elsewhere in this issue, we see how the great Eddie Lawson now has a working relationship with bicycle manufacturer Giant and is in thrall with the company’s e-mountain bikes. But for people like Steve Willgoose, the name Eddie Lawson will always be associated with his legendary GP and Superbike performances. Lawson’s influence even extends to the choice of restoration builds to which Willgoose now applies himself.

In our January 2019 edition we saw his treatment of a 1981 Kawasaki GPz1100. Brilliant work. As a stablemate to the GPz, Willgoose also reconstructed an Eddie Lawson-inspired 1982 KZ1000S1 to exacting measures. The goal being a streetified-resto that would be nut-and-bolt faithful to the factory production bike, a track-only homologation special of which there was only ever a handful produced. 

Kawasaki kz1000S1 static gauges

The numbers vary from source to source, but it’s safe to say that of this Kawasaki, less than 40 KZ1000S1s were ever built, and it’s rumoured that most of the still surviving units have made their way back to Japan and into the hands of collectors and even vintage series road racers.

Given its status as a very rare find indeed, you might assume Willgoose was pleased with his efforts to recreate a slice of history. Not the case.

“I started seeing things that were not correct on the bike,” he says. And with dissatisfaction preying on his mind, Willgoose returned to his shop on British Columbia’s Sunshine Coast. 

“I decided to make the bike really proper this time,” he says. “I stripped it down to the bare frame and got rid of the GPz frame. I then bought a 1982 J frame like the original KZ1000S1 racer had.”

Kawasaki kz1000S1 ride side profileThe KZ1000S1 was Kawasaki’s carbon copy of the bikes ridden by Eddie Lawson and Dave Aldana in their 1981-82 AMA campaign. According to the enthusiast website kz1000R.com, because most of Kawasaki’s race support resources were directed towards the European GPs it was decided that while the factory would develop the engine, Kawasaki mechanic Randy Hall would develop the chassis—the S1 featured an alloy swingarm of his design and Kawasaki would go on to release a modified KZ1000 Eddie Lawson Replica for street use.

Once he resolved to remake his build around a modified KZ1000J frame with the racing S1 mods, Willgoose spent the following year tracking down a “real S1” so he could get original race-frame specs.

Kawasaki_kz1000S1 static engine“I knew they started with a regular KZ1000J frame and then cut some things off the frame,” says Willgoose. “So I found myself a rear J frame and then spent many months getting all the (Randy Hall and Rob Muzzy) frame mods just right. The main ones are the engine brace and lower triple clamp stops. Then the new race prepped J frame went to the paint shop.” 

Working with photos and and magazine articles and the S1 replica frame with engine stiffeners, he says he “finally made the bike I always wanted.” Willgoose recoated the engine in all black ceramic, added a hollow chromoly swingarm pivot and mounted the race-repli header, megaphone and Kerker nameplate.

Kawasaki kz1000S1 static rear hubHe sourced other equally hard to find parts such as the proper rear caliper, genuine KZ1000S1 magnesium quarter-turn throttle and real S1 heat seamed seat. A replica S1 tapered fully open ignition engine cover and external ignition wire routing like the S1 are among the painstaking details Willgoose sourced or created in his pursuit “To make THIS bike the best it could possibly be.”

The front caliper hangers were done in billet and Willgoose installed “very close replica” quality Japanese steel brake lines and finished with “a full race safety wire job in .032.” Subsequent tuning and dyno runs confirmed a 22-horsepower gain.

“This bike is so very close to the real Works S1 bike now,” Willgoose says with understandable pride. “Word on the internet is that it has become one of the top three replicas in the world. So I’m super pleased with that.”

(Photos Doreen Wilgoose)

Kawasaki_kz1000S1 with rider

Canadian Biker #349 (2020)

RELATED: Kawasaki GPz1100

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