Father, Son, and ZRX: Kawasaki ZRX1200S

In the 2013 Pikes Peak International Hill Climb, professional road racer Jake Holden set the fastest time ever up the mountain on a carbureted motorcycle. The bike was a custom Kawasaki “ZRX1224RR” built by James Compton of SBK Factory (now James Compton Customs).

James, a Texas native, had a 12-year road racing career, competing in AMA Pro Superbike and Formula Extreme, before trading in his leathers to become a mechanic, tuner, crew chief, team manager, and bike builder.  Compton was the crew chief for Michael Jordan’s AMA Superbike team, and he’s worked with many of the top names in American superbike racing. In 2012, he left the AMA paddock to start his own business. 

“Compton’s vision is to create a new class of bike, blending the vintage superbike look with modern superbike technology.”

Enter our friend Sebastien “Seb” Vernaison of France’s Seb Kustom Motorcycle. A plumber by trade, Seb was introduced to motorcycles by his parents at a young age — they were both riders. In fact, his father’s love for the Kawasaki ZRX helped lead to this project:

“My father is a huge ZRX fan—he’s owned his since 1999—and I’ve always seen him looking at photos of customized ZRXs online. While searching for a base bike to customize, I came across a ZRX built by James Compton and remembered that my father had some photos of his work on his computer.”

Seb was inspired to build a similar machine, and the project would come full circle, as his own son was involved. 

“I actually contacted [Compton] to explain that I planned to build this custom bike with my 11-year-old son — who helped me with a few tasks. James loved the idea and sponsored us with some of the parts he manufactures; they’re available on his website.”

The modifications were extensive, aimed to transform the retro muscle bike into a much sharper machine. Seb’s given us a full build spec below. Highlights include Kawasaki Versys forks, KYB rear shocks with Hyperpro springs, Kawasaki Z750 wheels, radial brake conversion, Dynojet kit, Black Widow exhaust, James Compton USA PAIR (emissions control) delete and crankcase breather, and more. 

Then there’s the bodywork. Seb seems to have a penchant for bikes he can convert from one style to another in just a few minutes. Like his previous Honda Hornet 600 build, this ZRX is something of a changeling:

“I wanted a motorcycle that was both aggressive and versatile enough for various uses; I decided to set up two different headlight fairings so I could switch styles in ten minutes.”

He adapted and modified two fairings: a Kawasaki GPZ900 Ninja and a ZRX-R unit, which can be swapped in just 10 minutes. The tail section is custom, based on the original cowl, and the bike is running a modified Ricambi Weiss belly pan, satin-black frame paint, and a custom seat by C&R Création upholstery.

Seb says the bike is great to ride, and it turns heads wherever it goes.

“The engine is fantastic, and the sound is just as good! It certainly doesn’t leave passersby indifferent.”

But the best part might have been the building process itself…and who he had beside him.

“I really enjoyed building this motorcycle with my son. The part I enjoyed most was updating the chassis: changing the forks and front brake system, the rims (lighter and with a more modern design), and replacing the original rear springs with Hyperpro ones.”

It seems the two-wheeled passion often passes down from one generation to the next, and we wouldn’t be surprised if Seb’s son is one day building bikes of his own. Perhaps even a ZRX! 

Below you’ll find our full interview with Seb about the project, and more photos courtesy of Jx Shooting.

Kawasaki ZRX Restomod: Builder Interview

• Please tell us a bit about yourself, your history with motorcycles, and your workshop.

I work on my motorcycles in my spare time; I’m a plumber, and modifying my bikes is a real passion of mine.

• What’s the make, model, and year of the donor bike?

Kawasaki 1200 ZRX S from 2003.

• Why was this bike built?

I only work on my own personal projects; they are not client commissions.

• What was the design concept and what influenced the build?

I wanted a motorcycle that was both aggressive and versatile enough for various uses; I decided to set up two different headlight fairings so I could switch styles in ten minutes.

My father is a huge ZRX fan—he’s owned his since 1999—and I’ve always seen him looking at photos of customized ZRXs online. While searching for a base bike to customize, I came across a ZRX built by James Compton and remembered that my father had some photos of his work on his computer.

I started looking for a base bike and found one 900 km away; I didn’t hesitate to make the trip because the price was great and, above all, the bike had low mileage.

• What custom work was done to the bike?

Chassis Modifications:
– Kawasaki Versys forks
– KYB rear shock with Hyperpro spring
– Kawasaki Z750 wheel
– Nissin front master cylinder (brake and clutch)
– Oberon Performance clutch slave cylinder
– ZX10R front brake caliper with aluminum bracket for radial brake conversion
– Moto Master brake discs and pads
– Braided brake and clutch lines
– ABM rearset footpegs
-Aluminum clip-on handlebars
-Custom rear brake lever and license plate bracket

Bodywork:
-Adaptation and modification of a GPZ 900 Ninja fairing
-Adaptation and modification of a ZRXR polyester fairing (10-minute swap)
-Custom rear cowl based on an original cowl
-Modified Ricambi Weiss belly pan
-Custom steel front fender with fork tube protectors
-Satin black frame paint
-Anthracite gray metallic base coat, original-style bodywork decals
-Custom seat by C&R Création upholstery
-Vintage grips
-Oberon Performance fuel cap

Engine:
– K&N air filter
– Dynojet kit
– Unrestricted aluminum carburetor caps
– K&N oil breather
– Black Widow exhaust system
– ZX10R pencil coil
– Wagner Classic Oil engine and fork oil
– Acerbiss quick-action throttle
– Custom aluminum clutch slave cylinder bracket
– James Compton USA PAIR (emissions control) delete
– James Compton USA crankcase breather
– Custom aluminum battery tray
– Racing aluminum radiator with white silicone hoses

Electrical components:
– Kellermann Spot LED front turn signals
– Kellermann Dayron LED auxiliary lights
– Kellermann Spot 3-in-1 LED rear lights (headlights/brake lights/turn signals)
– Kellermann flasher unit
– Lithium battery

 

• Does the bike have a nickname?

Not really; I named the file on my computer “ZRX Replica” because I drew heavy inspiration from James Compton’s work. I actually contacted him to explain that I planned to build this custom bike with my 11-year-old son—who helped me with a few tasks. James loved the idea and sponsored us with some of the parts he manufactures; they’re available on his website.

• Any idea of horsepower, weight, and/or performance numbers?

The engine setup remains fairly close to stock; I simply derestricted the carburetor bank, installed a Dynojet kit, and fitted individual K&N air filters. I also installed a Black Widow exhaust system, which delivers a fantastic sound without being excessive.

• Can you tell us what it’s like to ride this bike?

It’s really great to ride this bike; the engine is fantastic, and the sound is just as good! It certainly doesn’t leave passersby indifferent.

• Was there anything done during this build that you are particularly proud of?

I really enjoyed building this motorcycle with my son. The part I enjoyed most was updating the chassis: changing the forks and front brake system, replacing the brake discs with Moto Master Brakes, which are more efficient and aggressive than the original ones. The rims (lighter and with a more modern design), and replacing the original rear springs with Hyperpro ones.

• Is there anyone you’d like to thank?

I would like to thank the partners who also supported this project.

-Kellermann
-Moto Master Brakes
-Ruroc
-K&N Filters
-C&R upholstery
-Wagner Classic Oil
-Poly26
-James Compton
-Bowtex
-Black Widow

Follow the Builder

Instagram: @seb_kustom_motorcycle
Photographer: @jx_shooting

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