Yamaha Ascot Scrambler Replica | Building the Beast

Ascot, Catalina, what’s the difference?

Noah may have taken only six months to build his arc, but we built this Yamaha Ascot Scrambler replica in just 90 days. Of course, I had a head start after finding a forlorn 1962 Yamaha YDS2 advertised on Craigslist by Century Motorcycles in San Pedro. The bike was complete but crustyjust the right starting point for a racer. Or so I thought: While resurrecting the chassis looked straightforward, the engine was a major unknown, and so I immediately dispatched it to Scott Clough Racing, builder of championship-caliber vintage two-strokes.

Its swamp-rat innards shocked even the wizened Clough. The engine-mounting studs were frozen, the iron cylinders and pistons were locked in a galvanic embrace, the bottom end was rusted, the clutch fried and the bearings toast. Scott managed to get the lump pried apart while I phoned, e-mailed and Googled my way across the U.S. looking for bits. N.W. Vintage Cycle Parts had pistons, rings and pins; Speed & Sport stocked a crucial shift-return spring; Champion Motorsports found larger YDS3 carbs; and eBay yielded OE cables. But little old Browns’ Cycles in Paso Robles yielded real unobtanium: NOS crankpins, bearings and rods.

While SCR built the engine up with a blazing-hot PVL electronic ignition from Penton Racing Products and a wicked set of upswept expansion chambers made from Rob North cones, the chassis was also getting some love. CIP Powder Coating turned the dingy frame into a ravishing black-and-orange Ascot Scrambler visage while Vintage Restoration resurrected a genuine Ascot Scrambler tank unearthed by Motorcyclist's own Thad Wolff. With the original badge recesses leaded in decades ago, stick-on Yamaha R1 emblemsalong with a commemorative Catalina decal designed by Jim Hatchfinished the cosmetics.

Race Tech rebuilt the 48-year-old fork and also built new adjustable-damping shocks, valved and sprung for the YDS2’s significant heft, turning a rideable bike into a raceable one for the Island. Meanwhile, billet Yamaha GYTR footpegs replaced the stock rubber-covered jobs, TAG Metal grips attenuated bar vibration and FMF Turbine Core II silencers satisfied Catalina’s spark-arrestor policy. It all came together just in time for a single test day at Zaca Station MX, thanks to some expert last-minute fabrication at Sport Cycle Pacific.

Maybe the piece de resistance was the Dunlop 4.00-18 trials tires. Seemingly better suited for a tractor than a vintage racer, these enormous skins hooked right up in the varied conditions, and the front tire simply laughed at such trifles as roots, rocks, mud, ruts and silt. Of course in the race, everything on this reborn replica worked so well that I was laughing right along with it.

AT1 tach was meant to help avoid breaking the thick rings on the YDS2 pistons, but the drive quit working the day before the race. Tanktop decal celebrates Yamaha’s first running of the event in 1958.
Larger 24mm YDS3 carbs gave the 48-year-old 250cc twin some extra kick. Without a front fender, the K&N; clamp-on filters were massively dirty after the 45-minute race.