FEATURE - 1980 Kawasaki KZ650 SR custom

Words: Mike Ryan

Photos: Sebastien Vernaison

The international reach of JUST BIKES never fails to impress. Since we started featuring custom bikes online and in the magazine, we’ve had builders from Japan, the USA, Spain, Germany, Sweden, the UK and Indonesia reach out to us, wanting to share their creations with our audience. Now, we can add France to that list.

Sebastien Vernaison may be a new name to many Aussies, but he’s not a newbie in the field of custom bike building.

Born in Lyon, Sebastien was tinkering with cars and bikes from a very young age, but a relocation to Pluvinger in Brittany (the westernmost part of France), saw him get more serious about custom motorcycles, establishing ‘SKM’ (Seb Kustom Motorcycles) a bit over a decade ago.

SKM isn’t a full-time gig for the talented Frenchman. During the week, Sebastien works as a plumber, so spanner time on bikes is an after-hours pursuit only – at least for now. But even with those restrictions, a string of interesting bobber and chopper-inspired builds came out of Seb’s shed, so he began to make a name for himself – and SKM - in his native France.

International attention came in 2019, when Sebastien was invited to exhibit a Yamaha XS650 custom at the Verona Motor Bike Expo in Italy; an annual event that presents 3,000 bikes and attracts more than 150,000 visitors.

Seb’s Yamaha from that show contained elements that have been carried over to the bike featured here, but the two are very different creations, both aesthetically and in terms of the base bike for the build, with a Kawasaki Z650 SR used this time around.

The Semi-Chopper

The success of Kawasaki’s original Z1 from 1972 spawned a range of variants, from singles to parallel twins and sixes, as well as sports bikes, cruisers and tourers. The Z650 (aka KZ650 in North America and some European markets) first appeared in 1976, when the Z name was white hot and it made sense to spin off smaller capacity versions of the big 903cc four.

Built around a 652cc DOHC air-cooled inline four, the Z650 was cast from the same ‘UJM’ (Universal Japanese Motorcycle) mould as the Z1, and like its big brother, the Z650 would later be offered in a “chopper” version, known as the ‘LTD’, which added taller handlebars, a sculpted two-up seat and smaller fuel tank, amongst other cosmetic changes.

For the Z650, Kawasaki also offered the ‘SR’; a model that was something of a halfway house between the conventional Z650 roadster and chopper-esque LTD in terms of styling.

Debuting in late 1978, the Z650 SR featured alloy wheels, with a smaller 16-inch rear wheel (18-inch on the standard Z650) and wider tyres, a long and deeply padded seat, taller handlebars, a reshaped fuel tank, dual front disc brakes, disc rear brake and cosmetic differences like painted instead of chromed mudguards, a chromed chain guard and chrome shells for the dual instrument pods.

Even though it was only on the market until 1981 (when it was replaced by the similar Z650 CSR), the SR was well received, as it offered some of the style of the more overtly chopper-inspired models without the compromises in comfort and everyday usability that come with that styling.

An Affordable Option

A scan through the listings on JUST BIKES shows classic Z650s were pretty thin on the ground at time of writing, and we’d suspect it’s much the same in Europe, so Sebastien was fortunate to acquire the example he did, although he wasn’t particularly looking for a Kawasaki as the base for this build.

“I was just looking for a motorcycle at a low price - I did not have a specific brand or model in mind,” Seb recalled.

The unit he found was a two-owner example, in good condition in all the important areas and cheap – an important consideration when you’re doing these builds out of your own pocket as Seb is.

A cheap entry price is the upshot of the Z650’s relative obscurity. Had Sebastien been looking to base this build on a Z1/Z900 from the same era, he’d be paying significantly more.

“The bike was mechanically good. The aesthetics weren't great, but it didn't matter, since I was going to modify it completely.”

Purchased in 2019, soon after Seb’s breakthrough appearance at the Verona Bike Expo, the bike took almost two years to build, primarily due to delays in the shipping of aftermarket parts and custom components as a result of the COVID-19 pandemic.

Ruroc . . . and Land Rover?

Normally, once a custom bike is built, people buy or decorate a helmet to match. But Sebastien went the other way for this build.

“The helmet was more or less the starting point of the project - at least for the colour,” Seb explained. “I had asked (UK-based helmet company) Ruroc to provide me with a camo-coloured helmet. To make this motorcycle’s new look, I applied a base colour like that of the helmet.”

The nearest match to that helmet colour was a khaki that came from the Land Rover colour palette.

Including the paint, this build’s “military” vibe was planned from the outset and included a shark’s mouth on the offside, in the style of WWII fighter planes, while a rising sun motif on the nearside echoes Japanese battle flags. Against this, a black finish for items like the wheels, frame, forks, rear shocks, pegs, levers and other parts suit the aesthetic and helps those graphics stand out.

“I thought that this decoration was very aggressive and also makes a small link with my old bike – the XS650 ‘Japan Style’ chopper.”

The graphics, applied by Sebastien’s friend ‘Cedric-B-Ink’n and the paint by ‘Tony the bodybuilder,’ were both to Seb’s design and it’s remarkable how true the finished product is to the original renderings.

“Nothing was changed from my original idea,” Seb affirmed.

But were getting a bit ahead of ourselves talking about the paint and graphics, which were the last and least troublesome parts of this build…

Adding Air, Incorporating Norton

Mechanically, the SR’s 652cc four was mostly unchanged for this project, at least internally. Same goes for the five-speed transmission with a chain final drive and the main frame area, but a LOT was done around this core.

For starters, a quartet of DNA filters were added in place of the original airbox and the factory 4-into-2 exhaust was replaced with a Delkevic compact 4-into-1 system.

At the front end, the factory Kawasaki forks were retained, but 10cm was cut from their length and a Harley-Davidson fork brace added, while at the rear, twin air shocks, also from a Harley-Davidson, was fitted in place of the factory twin coilovers.

While commonly seen on big cruisers and tourers, air suspension on a mid-size roadster like this is far more unusual. Incorporating the shocks, compressor and all the related plumbing and controls for the air system was only part of the challenge.

“Fitting this also required modification of the entire rear of the frame, in order to still be able to move the bike with the shocks in their lowest position,” Seb explained.

It wasn’t easy, but incorporating the air suspension was all part of delivering this custom’s low-slung look, as presented in the original renderings. Of course, the air shocks do allow the stance to be raised for rider comfort on the road, as well as keeping that underslung Delkevic exhaust from scraping the tarmac.

“Adapting the fairing was just as challenging,” Seb added.

That fairing, from French company Poly 26, was made to suit a classic Norton Commando, so needed significant modification to fit the Kawasaki, including reprofiling the handlebar openings and adding cut-outs to cater for the engine covers on each side. Sebastien also worked an LED headlight into this fairing and added a cut-down, reprofiled and tinted windscreen, too.

Compared to Sebastien’s XS650 build, the fairing on this Kawasaki is a big part of its “look,” serving as more than just a canvas for those WWII-style graphics.

Kawasaki, Kellerman and More

Moving to the fuel tank, that’s still the factory Kawasaki Z650 SR unit (which was a different shape to the regular Z650), but a pop-up style cap has been fitted and fuel level windows added on each side.

The seat is a full custom piece, made for Sebastien by La Derouillée Saddlery and trimmed in leather. It’s placed on a base and tail unit from a Kawasaki Z1000ST that’s been modified to fit, including a deleted tail light and cutout for the rear wheel when the suspension is at its lowest position.

Nestled into this tail section is a Krax Moto compact lithium ion battery for the bike’s electrics, which are all custom, including Kellerman front indicators, combination tail/stop/turn lights at the rear and a number plate light. Kellerman supported Seb’s XS650 build and were one of a number of companies to provide product, either for free or at cost price, for this build, too.

For the brakes, the factory discs have been retained at each end, but C1990s Kawasaki ZR750 calipers have been added at the front and a ZR750 master cylinder at the rear, with the rear brake caliper held in place with a section of candy twist bar steel. A Brembo PR19 front master cylinder, aviation-spec brake lines and a very neat brake fluid reservoir made up from a section of hose with a viewing window have also been added.

The wheels are the original factory units, too, but where Sebastien drilled sections of these on his XS650 build, he left them untouched here, apart from the black paint and a set of new Avon Cobra tyres.

Only the Essentials

Moving to the control centre, all the factory instrumentation is gone, along with the factory handlebars, levers, switchgear and master cylinder – befitting a stripped-down classic race bike. Dominating the space immediately in front of the rider is an Autometer tachometer with an offset shift light. Incorporated into the tacho itself are warning lights for high beam, neutral and the indicators.

Tucked in below this is a pressure gauge for the air suspension, while switches have been cleverly incorporated into the top fork yoke in place of the handlebar mounts – an engine killswitch on the left and control to raise and lower the rear shocks, along with an oil pressure warning light, on the right.

The clip-ons carry retro-look white grips, Brembo levers and mini switches for the indicator, headlight and engine start. Rearsets keep the race theme going and there’s enough of a backstop in that custom saddle to keep the rider firmly planted at speed.

With so much removed from this bike, and what’s gone back on being minimalist or lightweight, Seb estimates his creation is between 15 and 20kg lighter than a stock Z650 SR.

Road Burner, Head Turner

You’re probably questioning whether such a stripped down, spiced up custom like this is legal for French roads. JUST BIKES asked the same question and Seb said it is – sort of.

“For the moment, it is tolerated to ride in France with modified motorcycles, but you need to be really quiet about it. I installed the legal minimum front and rear indicators, plus licence plate lighting and mirrors.” (NB: these aren’t fitted in the photos)

Sebastien originally planned to have this bike completed in time for the 2020 Verona show, but a series of small delays turned into much bigger ones when COVID hit, meaning parts that normally took days or weeks to arrive now took months. Ultimately, this build was completed almost two years after it started, making its debut at last year’s edition of the Verona Motor Bike Expo, followed by many other bike events throughout 2022.

Seb says he’s rapt with the finished result, despite the delays.

As a bike to ride, it’s apparently a lot of fun, but it’s the look of this build that most impresses Seb – and other people, too.

“I really like the ‘compact’ effect of the bike, and especially the way people look at it when I ride it,” Seb laughed.

“I also love the decoration that was done by my artist friend, Cedric-B-Ink. He did a lot of detail work and wasn’t content to simply apply the colours to make the drawings.”

Those details include a weathered look to the front and side graphics, as if the bike’s been in battle, as well as Seb’s ‘SKM’ logo on the sides of the tank and a nod to the build’s supporters on top of the tank. Those supporters included Kellerman, DNA, Ruroc, Wagner Classic Oil, Fictech and T4.

In addition to Cedric-B-Ink, Sebastien also extended his thanks to Tony the bodybuilder, who did the paint.

When Seb first brought this custom Kawasaki to our attention last year, he'd already acquired a Suzuki GSX-R 1100 for his next project. That build was close to completion at time of writing, but funding it means the Kawasaki will be sold.

If it takes your fancy, you can email Sebastien at: [email protected] to confirm if it’s still available and talk price.

As mentioned at the top of this article, this is the first custom that’s come to us from France, so we thank Sebastien for that and hope to see more builds from République Française in the future.