Alex Winkler wears many hats. By day, he’s an industrial mechanic—but by night, he uses those skills to work in his home garage, restoring and rebuilding vintage bikes. As the weekends passed, Alex drove his creations out of the garage and into the race.
While we can all appreciate the free gallery building, there’s something special about the home-made custom built to drive. Alex lives and breathes this philosophy. Both cars you see here—one from 1978 YAMAHA SR500 and a 1980 Yamaha XS650—also happens to be his personal flat road racers.
Based in Stuttgart, Germany, Alex has been building his own bikes for the past 10 years called Twinshock Motorcycles. The SR500 was actually one of the first motorcycles he tried on. Initially, he bought the car for about $900 on eBay, with the intention of making a cafe racer out of it.
It was in rough shape and barely ran, so Alex started by rebuilding the engine, increasing displacement to 620 cc in the process.
He also tackles the work on the cylinder head himself, including shifting, polishing, and machining to accommodate larger valves. The Megacycle Performance Cam has been set to good measure.
Alex also added a completely hand-made exhaust system, from the manifold to the silencer. A new Mikuni TM40 flat-slide carburetor has been added, and the stock airbox has been swapped out for a less restrictive housing filter, to keep things running smoothly.
By the time the engine came back on, the little cafe racer was running like a champ and hitting a healthy 49 hp… but it didn’t stay in the coffee state for long. A few years later, Alex became interested in flat road races, and once again the little Yamaha hit the road.
The front end is upgraded with Yamaha XT550 forks, while Koni 7610 shock absorbers can be adjusted at the rear. Alex kept the standard 19” front wheel of the SR500 but attached the KTM 3.00×19” rim to the rear axle. That means he can fit Mitas H18 flat road tires on both ends.
The fiberglass fuel tank and flat tail section are located on top. Alex completed the build with a custom brake and sprocket guard, a machined rear unit, and a homemade fork stabilizer to aid handling in race use.
As Alex continued to craft and tinker over the years, his spare parts collection has survived on its own. At some point, he realized he had everything he needed to build a second Yamaha track bike—so he did it spontaneously.
Legally, the white motorcycle you see above is a Yamaha XS650, but it’s the same XS size as your typical puppy Labrador Retriever. We’re not complaining about this hybrid dog’s pedigree, though, because Alex has worked some serious magic with his bin of parts.
Technically, you’re still looking at an XS650 engine housed in an XS650 chassis. Alex drilled the cylinders to 840 cc, and fitted a pair of Wahl Spezialkolben pistons (German for ‘special piston’), with a set of Nissan Bluebird (yes, car) cylinder pins. There’s also a performance ignition from Boyer Brandsden.
The carburetor is a Mikuni TM36 slider, K&N filters and a fully custom exhaust system. According to Alex, the engine now makes 68 sturdy horses—which isn’t too shabby, since the bike has been reduced to just 340 pounds.
The original front wheel has been replaced with a spare 19-inch SR500 rim that Alex has available, which now sits between a set of first-generation Yamaha FZR1000 forks that also happen to be placed around. The entire rear end is also assembled from spare parts, including a rear swingarm from a Yamaha SRX600, a rear wheel from a Suzuki RMZ and another Koni 7610 shock absorber.
The bodywork includes a custom painted fuel tank from a Suzuki GT50 and a chunky rear fender. The XS also features the first seat that Alex has sewn together himself. It’s a beautiful two-piece leather piece and sits on a custom subframe.
Alex had a nice Brembo brake setup from a KTM 690 Duke stowed away, so he machined a custom bracket and put it to work in the rear. It’s a similar story (albeit much more difficult to install) for Yamaha’s new hydraulic clutch system, taken from an unspecified Ducati at some point in the last decade.
There’s no shortage of hand-machined parts scattered throughout this build. They all carry the same unmistakably ergonomic design that Twinshock Motorcycles builds share—like numerous ‘speed holes’ for added lightness.
Notably, there isn’t a single inch of CNC machining on either of these bikes. Alex refuses to use digitally assisted methods, preferring to craft everything by hand to keep his works as “classic” as possible.
These two classic Yamahas make a nice pair, but we bet they look even better in motion. The fact that they have to race almost every weekend and still clean this up, gets a big boost from us.
Twinshock motorcycle Instagram | Pictures of (and thanks) Kati Dalek
