dimensions (same as the Adler, and
repeated in Yamaha’s YDS-1), with the
pistons running in heavily finned, deep-
ly spigoted cast iron barrels topped with
light alloy cylinder heads. A single 7/8-
inch Amal Monobloc type 375 carbure-
tor fed the engine with 25:1 premixed
“petroil” fuel. Alloy connecting rods
with roller bearing big ends ran on two
separate built-up crankshafts that were
bolted together during assembly and
“timed” at 180 degrees by a keyed taper.
The crank assembly fitted into die-
cast cases with the primary drive and transmission cast in
unit. Drive to the clutch and 4-speed gearbox was by chain.
The complete drivetrain was suspended from the beam frame
by a cast lug behind the barrels that also doubled as the air
intake and carburetor mounting. The frame wrapped around
the rear of the power unit, and also carried the rear swing-
arm pivot. The swingarm itself carried
mountings for the full-enclosure chain
guard, and was controlled by a pair of
Armstrong spring/damper units bolted
to the rear frame.
There was no triple tree at the front.
The head stem was brazed into a steel
casting that also carried the fork legs,
which contained a trailing-link suspen-
sion controlled by Armstrong shocks.
The whole front end arrangement owed
more to contemporary scooter prac-
tice than motorcycle convention. More
familiar, though, were the 16-inch WM2
wire wheels, both fitted with 6-inch
single-leading-shoe drum brakes.
The finished Leader did look more
like a big-wheel scooter than a contem-
porary motorcycle. The full-enclosure
bodywork included a dummy gas tank
that actually contained a luggage com-
partment, with the actual fuel cell being a rectangular steel
tank under the seat. An optional full windshield could be
fitted, together with hard luggage, turn signals and a clock
mounted in a full dashboard. The rear bodywork hinged
upward (after releasing the muffler stays) to give access to
the rear wheel. Think Honda’s PC800 Pacific Coast, perhaps ...The single Amal Monobloc carburetor
(far left). The headlight nacelle
features a speedometer and an
ammeter (left). The Ariel logo is
featured on the handgrips (above).