Get Dirty: A Kawasaki W800 with a vintage motocross vibe

Kawasaki W800 vintage motocrosser by MRS Oficina
The Kawasaki W800’s versatility is just one of its many charms. Throw a handful of mods at it, and you’ll end up with a respectable garden variety street scrambler in no time. But how about turning it into a full-on vintage motocrosser, where the original bike is almost unrecognizable?

That takes equal doses of imagination, talent and dedication—and Mário Raphael Soares has plenty of all three. He’s been running MRS Oficina in Paris for the last few years, but has just moved his workshop back to his home town of Chaves, in Portugal.

Kawasaki W800 vintage motocross bike by MRS Oficina
This Kawasaki W800 was his fourth collaboration with Kawasaki France, and the last project to roll out of his Parisian shop.

The idea was to build a retro scrambler with a motocross vibe, purely for off-road use and with some actual capability. The overall aesthetic recalls an era rather than any one particular bike—but if it wasn’t for the modern suspension and fresh paint, it would easily pass for a vintage stocker.

Kawasaki W800 vintage motocross bike by MRS Oficina
It took more than just a few nips and tucks to achieve this look though. For starters, Mário had to shorten and narrow the stock tank to get the proportions just right. That left too little room for both the fuel pump and a decent amount of gas to occupy, so he also built an auxiliary tank under the seat to hold the pump.

Mário made some subtle tweaks to the frame, but kept its long, kinked rear loop, simply adding a new tab for the rear fender. Up top is a stubby new seat, and on the sides are a pair of hand-made aluminum number boards. The vintage trials-style fenders are custom too, hand-rolled on Mário’s English wheel.

Kawasaki W800 vintage motocross bike by MRS Oficina
The W800’s classic bodywork is complemented by a thoroughly modern parts spec. Up front, Mário grafted on the yokes and upside-down Showa forks from a Kawasaki KX450F.

For the back, he sourced an aftermarket aluminum swingarm, then shortened it by a few inches and welded on new shock mounts. It’s connected to a pair of custom-built Öhlins shocks, measuring longer than stock.

Kawasaki W800 vintage motocross bike by MRS Oficina
The wheels consist of 21F/18R Excel rims laced to Talon hubs, and wrapped in Bridgestone ‘cross tires. Mário fitted a full brake system from project sponsor Beringer—including the discs, calipers and master cylinders, with a custom plate to position the rear caliper.

You’ll also find Beringer controls up top, mounted along with Renthal handlebars and grips. And since this Kawasaki doesn’t need to run on the street, the wiring’s been simplified right down to just a start button and kill switch.

Kawasaki W800 vintage motocross bike by MRS Oficina
With 400 hours of labor in this project, you can bet that every last detail’s been seen to. There’s a custom bash plate low down, and if you peek around the front you’ll even spot a custom brake line guide mounted to the bottom yoke.

There’s also a set of grippy KX450F foot pegs, and a chain guide out back to account for the radical new swingarm angle.

Kawasaki W800 vintage motocross bike by MRS Oficina
The twin exhaust system is a stainless steel job, also fabricated by Mário. It includes hidden dB killers to keep the noise levels reasonable, and bungs to mount the OEM emissions sensors, so that the fuel-injected twin will run smoothly. A pair of foam filters take care of business on the intake side.

The W800’s parallel twin motor is arguably its prettiest feature. But it takes a back seat here—sitting quietly inside this stunning little ‘crosser, and almost passing for a single at a distance.

Kawasaki W800 vintage motocross bike by MRS Oficina
Mário handled everything on this build himself, save for the upholstery and paint. It’s a killer livery too, with a palette borrowed from the 1980s KX500. It’s complemented by a few raw aluminum parts, and a subtle blue finish on the frame.

The details are equally slick—from the ‘W’ motifs on the seat, to the CNC-machined ‘MRS Oficina’ tank badges that mimic the stock W800 items.

Kawasaki W800 vintage motocross bike by MRS Oficina
As an extra nod to the marque, Mário’s embossed a set of ‘ones’ into the number boards, representing Kawasaki team rider Eli Tomac’s dominance in the 2020 AMA Supercross championship. Add it all up, and the final effect is nothing short of inspired.

Now let’s hope that this delightful throwback spends more time getting dirty, than it does on display.

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Kawasaki W800 vintage motocross bike by MRS Oficina