This year is off to a small start… for us, at least. As the new year revs up and fresh custom motorcycles start hitting our desks, it’s clear that small bikes with big attitudes are the flavor of the month. And we’re here for it.
This mini motocross bike from Wilco Lindner makes a strong case for dynamite coming in small packages. At a glance, it looks like a regular kids’ motocrosser—but the OEM-like plastics and Honda logos are red herrings. Lurking underneath them are the bones of a 2022 KTM 65 SX, an upgraded engine, and a smorgasbord of bespoke parts.
Wilco, who operates under the moniker A Nineteen Built, has a thing for minibikes. So when he developed an itch to build a motocross bike, he figured he’d build something that he could race in the minibike class in The Netherlands, where he’s based. “I like making stuff that’s different,” he quips.
“I wanted it to look like a somewhat factory MX bike. But after looking a bit closer, you should rethink that and wonder what crazy mind put this thing together. And that’s exactly what happened when I took it on its first outing.”
At the heart of this belligerent beasty sits the transplanted two-stroke motor from a Derbi moped. The 80 cc donk was treated to an extensive array of mods by Eddy at EHR Tuning—a world-champion two-stroke tuner in the Netherlands. It now sports a V-Force 3 reed valve and intake kit, modified cases, a ported cylinder, a special connecting rod, and some sneaky CNC work.
Eddy also installed a programmable ignition and then tuned the bike on his dyno. Wilco fabricated the exhaust and modified a Yoshimura muffler to terminate it. Other upgrades include a 28 mm carb, and an upgraded clutch that Wilco admits is still not strong enough.
Shoehorning the new engine into the KTM 65 SX frame required more than just a few tweaks. So Wilco went all-in until the only bits left were the upper frame tube and the steering neck. The lower frame sections and subframe are handmade parts, as is the swingarm.
Since the engine swap left no room for the original shock position, Wilco converted the rear suspension from a mono- to twin-shock setup, with a pair of YSS shocks propping up the tail. Up front, the OEM WP Suspension forks were lengthened with extenders from Ozzo Racing, then tuned by 4 Stroke MX Service to accommodate Wilco’s 90-kilo [198-pound] frame.
The new layout also called for a revised fuel tank and air box, so Wilco fabricated both of those out of aluminum. He made a pair of aluminum side panels too, then cut up the stock KTM 65 SX plastics and re-fitted them to finish the bodywork off. The cockpit is standard motocross fare; Renthal bars and grips, with Acerbis hand guards.
From this point on, Wilco’s minibike motocross bike became a family project. His little sister runs a MX graphics and apparel design company, Fresh Design, in The Netherlands. So Wilco leaned on her for all of the bike’s graphics.
“She came up with the idea of doing two pairs of radiator shrouds, so the bike has two completely different looks,” he tells us. “She even made stickers for underneath the seat.”
Their dad jumped in to paint the frame, while their mom upholstered the custom gripper seat cover. Wilco fabricated the seat pan, complete with a polished finish and riveted plates to hold everything together. “I know, a bit crazy—but totally worth it when you change air filters in between rides,” he adds.
Remarkably, Wilco wrapped the project up in under six weeks—with a trip to Los Angeles and a shakedown in Spain thrown into the mix. “A good friend of mine, who doesn’t need to be named, was kind enough to sponsor me a lot of parts,” he tells us. “Without him, this wouldn’t have been possible in such a short time frame.”
“I also have to thank my friend Jack, who helped me out in the last week between LA and Spain, by getting it to a point where I was able to take it with me and finish the last bits on holiday.”
“It was a week of sleepless nights and zero breaks, but it was all worth it after firing it up and ripping around the track in Spain. I’ve never had this many eyes looking at me while riding around an MX track… it stole the show.”
A Nineteen Built Instagram | See more of the build process on Wilco’s YouTube channel
