1935 AJS V4 Replica

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Dan started with a solitary black-and-white photograph and a cutaway drawing — not an engineering drawing but a line drawing showing the general layout of the engine internals.
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Dan Smith's 1935 AJS V4 replica based on the prototype of a motorcycle AJS never offered for sale.
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The V4 burst into life with a throaty rasp from the four exhausts — not smooth like an inline four, but with a ragged bea
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Magneto plate shows "AJ4."
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It’s hard to believe this isn’t a restored original, but it couldn’t be, as AJS never put its V4 into production. Excepting the hand built engine, the rest of the bike is period-correct, with most parts sourced from a mid-1930s AJS 350cc sidevalve single.
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Dan Smith with the finished bike.
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Trial fitting cylinder heads and cylinder patterns to engine case.

1935 AJS V4 Replica
Engine:
495cc air-cooled SOHC 50-degree V4, 50mm x 63mm bore and stroke, 10:1 compression ratio, 40hp @ 6,000rpm (est.)
Carburetion: Two Amal with dual remote floats
Transmission: 4-speed, chain final drive
Electrics: 6v, DC generator, dual twin-spark magneto ignition
Frame/wheelbase: AJS “Denly” single downtube steel frame/55in (1,397mm)
Suspension: Girder fork front, rigid rear
Brakes: SLS drum front and rear
Tires: 100/90 x 19in front, 100/90 x 18in rear
Weight: 450lb (205kg)
Seat height: 29in (737mm)
Fuel capacity/MPG: 5gal (19ltr)/NA

The word “unique” has a simple meaning: it means there’s only one of a kind. Things can’t be “quite unique” or “almost unique.” Either they are or they aren’t. Take Dan Smith’s AJS V4. It’s unique. There’s only one. And that’s because Dan built it himself.

Many of us can turn a wrench to do basic bike maintenance. Some of us are capable of restoring a rusty barn find to its original state, perhaps even making parts where the originals no longer exist. But very few of us can build a complete motorcycle engine from bare metal.

With the aid of drawings, a capable machinist could probably shape the parts from billet using CAD and a CNC mill. But what if there were no drawings, or even a model to work from? That didn’t stop Dan, who designed, cast, machined and assembled his V4 from a black-and-white period photograph and a cutaway sketch of the 1936 prototype. Oh, and if you didn’t know AJS built an air-cooled V-4, you’re not alone!

Motorcycle Classics Magazine
Motorcycle Classics Magazine
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