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In the event you undergo from the misunderstanding that Germans don’t know find out how to have enjoyable, you’ve clearly by no means skilled the German dash racing scene. Occasions like the favored Glemseck 101 are stuffed to the brim with wild and inappropriate bikes, all of that are assured to make you smile. And what may very well 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.
Norbert doesn’t completely work on English autos although—he’s restored a lot 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 arrogance to aim this zany twin-engine Yamaha RD350 construct. However the inspiration for the venture goes even additional again than that.
“I’ve been concerned with drag racing for the reason that early 70s,” he tells us. “What you’d see on the time in movies from the USA, you would then see in actual life on the US Military airbase close to Hanau. The drag racing dates had been at all times introduced on a Saturday morning on the army radio station.”
“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 need to injury 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 thought 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 received cracking.
The work wanted to show two RD350 mills into one four-cylinder stonker may 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 totally 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 might look approach cooler.
Intensive work was executed 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 aspect 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 way 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 seems to be bananas and sure screams like a banshee.
It’s clearly tough to wedge an engine of this dimension into a daily motorbike chassis, so Norbert constructed a brand new body from scratch. First, his buddy Heinz Lange drew the body in line with 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 had been lifted from a Nineteen 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.
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 components. A single Yamaha RD350 tachometer dominates the cockpit.
With contemporary 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 seems to be psychological—and, extra importantly, it seems to be prefer it means enterprise. However is it fast?
The reality is, Norbert doesn’t know but. He’s solely simply buttoned it up, and is but to begin testing and tuning it. However as soon as he has, he plans to unleash it on the traditional racing circuit.
If we had been his opponents, we’d be very afraid.
Photographs by, and with due to, Marc Holstein
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