Two-stroke terror: A twin-engine Yamaha RD350 drag bike


Twin-engine Yamaha RD350 two-stroke drag bike
When you undergo from the misunderstanding that Germans don’t know the best way to have enjoyable, you’ve clearly by no means skilled the German dash racing scene. Occasions like the favored Glemseck 101 are crammed to the brim with wild and inappropriate bikes, all of that are assured to make you smile. And what could possibly be extra enjoyable than a twin-engine Yamaha RD350 drag bike?

This mad machine is the brainchild of Norbert Prokschi, a grasp mechanic based mostly within the small Bavarian city of Johannesberg, simply east of Frankfurt. He’s spent the final 37 years restoring traditional British vehicles and bikes; every part from Jaguars and Morgans to Nortons and Vincents.

Twin-engine Yamaha RD350 two-stroke drag bike
Norbert doesn’t solely work on English automobiles although—he’s restored plenty of Japanese and Italian bikes too, and has been racing Yamaha TZ two-strokes for the previous 5 years. It’s his expertise with rebuilding these TZ motors that gave him the boldness to try this zany twin-engine Yamaha RD350 construct. However the inspiration for the undertaking goes even additional again than that.

“I’ve been involved in drag racing because the early 70s,” he tells us. “What you’d see on the time in movies from the USA, you possibly can then see in actual life on the US Military airbase close to Hanau. The drag racing dates have been at all times introduced on a Saturday morning on the navy radio station.”

Twin-engine Yamaha RD350 two-stroke drag bike
“About 20 years in the past I found an unique dragster from the 60s at an auto jumble in England. I restored it, however to date I’ve not had the chance to make use of it, since I don’t wish to harm this historic machine.”

Norbert’s hesitance to race his classic drag bike prompted him to construct one thing that he wouldn’t thoughts hurling down the strip. So he got here up with the concept of mixing a pair of two-stroke Yamaha engines into one beastly energy plant and sticking it in a bespoke body. With two 1974 Yamaha RD350 engines in hand, he bought cracking.

Twin-engine Yamaha RD350 two-stroke drag bike
The work wanted to show two RD350 mills into one four-cylinder stonker might fill volumes, so Norbert’s simply given us a broad overview. He began by splitting the instances of the 2 parallel-twin motors, then CNC-machined adaptor plates to mate them collectively. Then he grafted items from three completely different crankshafts collectively to create a single four-cylinder crankshaft.

Not content material to cease there, Norbert additionally flipped the center two cylinders round. He did this to make it simpler to accommodate 4 separate exhausts, but in addition as a result of it will look approach cooler.

Twin-engine Yamaha RD350 two-stroke drag bike
In depth work was performed on the cylinders, and the compression ratio was elevated within the course of. Norbert ditched the unique RD350 six-speed transmissions, favoring a single five-speed gearbox from a classic Yamaha R5. It sits on the right-hand facet of the bike, together with the gear shifter.

The carbs are trendy aftermarket items and are barely bigger than the originals. Every cylinder exhales by means of its personal exhaust; Norbert had the headers, growth chambers, and silencers made to his spec by a British firm, then welded every part up himself. It appears bananas and certain screams like a banshee.

Twin-engine Yamaha RD350 two-stroke drag bike
It’s clearly tough to wedge an engine of this measurement into an everyday bike chassis, so Norbert constructed a brand new body from scratch. First, his buddy Heinz Lange drew the body based on Norbert’s necessities. Then the 2 of them arrange a jig and fabricated the hardtail body out of metal tubing.

The entrance forks and 18” wheel have been lifted from a Eighties Honda MBX80, whereas the 18” rear wheel comes from a first-gen Suzuki GSX-R750. A steering damper and custom-made fork brace add stability to the entrance finish, whereas disc brakes at each ends deal with stopping duties.

Twin-engine Yamaha RD350 two-stroke drag bike
Norbert fabricated the Yamaha’s aluminum gasoline tank and, uhm, ‘seat.’ He made the foot controls and linkages himself too, however the handlebars, grips, and switches are aftermarket elements. A single Yamaha RD350 tachometer dominates the cockpit.

With recent paint on the body and exhausts, however nowhere else, Norbert’s engineering and fabrication are on full show. His 700 cc two-stroke drag bike appears psychological—and, extra importantly, it appears prefer it means enterprise. However is it fast?

Twin-engine Yamaha RD350 two-stroke drag bike
The reality is, Norbert doesn’t know but. He’s solely simply buttoned it up, and is but to start out testing and tuning it. However as soon as he has, he plans to unleash it on the traditional racing circuit.

If we have been his opponents, we’d be very afraid.

Photographs by, and with due to, Marc Holstein

Twin-engine Yamaha RD350 two-stroke drag bike


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