Piatti Scooters and Design

Today in Motorcycle History

Piatti Scooters

Manufactured: 1948-1956

A Scooter designed in 1949 by engineer Vincenzo Piatti, designer of the Minimotor auxiliary motor.

Named the S 125, it had a single-cylinder 124cc two-stroke engine with three-speed gearbox and chain drive.

The frame is a monocoque unit built of sheet metal on a single tubular skeleton from which the engine is suspended. The wheels are mounted cantilevered and are interchangeable, while the front suspension is biscuits oscillating lower and the rear is formed by the oscillating block motor-gearbox-transmission. The Piatti scooter was built in Britain and Belgium under license.

Villiers 17T/20T/25T engines also used his his patented designs, of which he had not a few. Piatti also designed engines for Vespa. AMC (UK) also used his designs, but these engines were not highly regarded. These engines were fitted to several Francis Barnet models, and apparently the Sturmey Archer engine fitted to Raleigh RM1 and RM2 mopeds between 1958 and 1960 were designed by, or based on the design of, Piatti.

The ground-breaking TSCC (Twin Swirl Combustion Chamber) in the 4 valve Suzuki GSX engines of the 1980's. Also Piatti.

Vincenzo Piatti worked with Ettore Bugatti, and later identified the "tumble" effect in combustion chambers (he called it Twinspin) some three decades before the concept was accepted by the automotive establishment. His engineering skills have resulted in the Ford Piatti and Saab Piatti engines.


ENGINE: Piatti 125 c.c. (51 x 61mm) single-cylinder two-stroke. Caged needle-roller big-end bearing. Crankshaft supported in one needle-roller bearing and ono single-row journal ball bearing. Light-alloy
cylinder head. Compression ratio, 7.2 to 1. Petroil lubrication.

CARBURETTOR: Amal Monobloc type 363/3 with air filter and strangler.

IGNITION and LIGHTING: Wico-Pacy flywheel magneco with six- volt lighting coils. Wico-Pacy 4 1/2 in-diameter headlamp with 24/24 watt
bulb. Dry battery for parking lights,

TRANSMISSION: Three-speed gear box in unit with engine; twist-grip control. Gear ratios: bottom. 12.6 to 1; second, 6.9 to 1; top, 4.5 to 1. Single-plate engine-speed clutch with cork inserts running in oil.
Transmission by 3/8 x 0.225in chain in oil-bath case. Rear wheel driven direct from gear box. R.p.m. at 30 m.p.h, in top gear, 3,250.

CONSTRUCTION: Monocoque body formed by steel pressings welded together; weathershield and footboards bolted to main structure. Engine-
transmission unit pivoted in Silentbloc bushes.

FUEL CAPACITY: 1 1/2 gallons.

WHEELS and TYRES: 7in-diametcr pressed-steel wheels with split rims carrying 3.50in-scction Dunlop tyres.

BRAKES: 4 3/4in diameter x 9/16in wide front and rear,

SUSPENSION: Leading-arm front suspension controlled by coil spring. Engine, transmission and rear wheel pivoted as a unit, controlled by
coil spring in tension; three-position adjustment for load.

WHEELBASE: 35in unladen. Ground clearance, 4 1/2in unladen.

SEAT: Foam-rubber, cushion-type dual-seat; unladen height, 30in (adjustable between 28 and 32 1/2in).

WEIGHT: 196 lb equipped with windscreen and basket and with half a gallon of petroil.

PRICE: £112 1 0s. With purchase tax (in Great Britain only), £139 10s.

Windscreen £4 10 extra; parcel basket £1 1s extra.

ROAD TAX: 17s 6d a year; 4s l0d a quarter.

MAKERS: Cyclemaster, Ltd., Tudor Works, Chertsey Road, Byfleet, Wcybridge. Surrey.

DESCRIPTION: The Motor Cycle, 24 May 1956.


MEAN MAXIMUM SPEED:   Bottom 19 m.p.h.

Second 29 m.p.h.

Top 38 m.p.h.

HIGHEST ONE-WAY SPEED: 40 m.p.h, (windscreen fitted; tail wind).


  • 10-20 m.p.h. 15-25 m.p.h. 20-30 m.p.h.
    Second ...... ...   4.5 sec   5.5 sec —sec
    Top...... ...... 10.6 $cc   10 sec 13 sec
    Mean speed at end of quarter mile from rest: maximum.
    Mean time taken from rest to 30 m.p.h, (through gears): 14 sec.

PETROIL CONSUMPTION: At 20 m.p.h., 115 m.p.g.; at 30 m.p.h., 95 m.p.g,

BRAKING: From 30 m.p.h, to rest 37ft (surface, dry tarmac).

MINIMUM NON-SNATCH SPEED: 9 m.p.h, in top gear.

WEIGHT PER C.C.: 1.56 lb.

Sources: MC Storico Conti, et al.

If you have further information or a query about Piatti please contact us