1935-1936

Cotton 1935 racer 350cc

By 1935, Cotton had firmly established itself as a specialist manufacturer of high-performance sporting motorcycles. The 350cc Racer models represented the competitive heart of the marque.

Engine and Performance

The 1935 350cc racing models were typically powered by JAP or Blackburne overhead-valve engines, often in twin-port configuration.

Capacity: 348–349cc (350cc class)
Engine Type: Single-cylinder OHV
Carburation: Amac racing carburettor
Power Output: Approximately 22–26 bhp (depending on specification)
Transmission: Hand-change gearbox
Final Drive: Chain

The twin-port cylinder design improved breathing and combustion efficiency, delivering strong mid-range torque and impressive acceleration for the period.

Frame and Handling

What truly set the Cotton 350 Racer apart was the patented triangulated frame.

Unlike conventional diamond frames derived from bicycles, Cotton’s design offered:

Superior torsional rigidity
Reduced flex under racing stress
Precise steering response
Excellent cornering stability

This chassis advantage made Cotton machines particularly competitive on technical road circuits and hill climbs.

Racing Reputation

By 1935, Cotton advertising proudly highlighted:

3 Isle of Man TT victories
4 second places
3 third places

The 350cc class was central to this reputation. The Cotton 350 Racer was a favourite among private entrants and club competitors who valued handling precision over outright engine size.

Typical Racing Specification

A competition-prepared 1935 Cotton 350 would often include:

High-compression piston
Racing magneto
Lightweight mudguards or none
Minimal lighting (or none for track use)
Narrow racing saddle
Close-ratio gearing

These machines were frequently factory-built to order, tuned to the purchaser’s requirements.

Historical context

In the mid-1930s, British racing was highly competitive. Manufacturers such as Rudge, Velocette, and Norton were active in the 350cc class.

Cotton distinguished itself not through mass production, but through engineering philosophy: handling as a competitive weapon.

The 1935 350cc Racer represents the mature expression of pre-war Cotton design, combining Blackburne or JAP performance with one of the most advanced chassis concepts of the era.

Model 30/B – Blackburne 250cc OHV

This model featured a 250cc Blackburne engine, combining reliable performance with Cotton’s rigid and lightweight chassis design.

Model 6/B – Blackburne 250cc OHV

A Blackburne-powered lightweight variant designed for steady performance and excellent road holding in everyday riding conditions.

Model 1/V – Villiers 148cc Two-Stroke

A lightweight and economical motorcycle fitted with a 148cc Villiers two-stroke engine. Designed for daily transport and new riders, it retained Cotton’s superior frame rigidity.

Model 2/V – Villiers 246cc Two-Stroke

A mid-capacity two-stroke offering increased power while remaining economical and easy to maintain.

Model 1/B – Blackburne 150cc Sloper

A compact model featuring an inclined (“sloper”) Blackburne engine, improving weight distribution and lowering the centre of gravity.

Model 1/J – JAP 150cc Sloper

Similar in concept to the Blackburne version but powered by a JAP engine. The sloped engine layout enhanced stability and handling precision.

Model 2/J – JAP 250cc Sloper

A 250cc inclined-engine model providing improved performance while maintaining balanced handling characteristics.

Model 2/JC – JAP 250cc Sloper (Competition Specification)

A sport-oriented variant of the 250cc sloper model, likely featuring higher compression or competition tuning.

Model 7/J – JAP 350cc Sloper Super

A more powerful sloper configuration with a 350cc JAP engine. Designed for sporting riders seeking stronger performance.

Model 8/J – JAP 500cc Sloper Super

The largest of the sloper series, powered by a 500cc JAP engine. It combined high output with Cotton’s characteristic chassis stability.

Source: Olympia Show
The Olympia Show was one of the most important motor and motorcycle exhibitions in Britain during the early 20th century. Held annually in London, it was the main event where manufacturers officially presented new models, technical innovations, and racing machines to the public, the press, and the industry.

Source: The Motor Cycle
The Motor Cycle was a leading British motorcycle magazine and one of the most authoritative publications of its time. Its reports, road tests, and show reviews are today considered valuable historical documents, widely used by historians and collectors as reliable primary sources on early motorcycle development.

Source: Motor Sport Magazine

Motor Sport is one of the world’s oldest and most respected motor racing publications, founded in the United Kingdom in 1924. Its contemporary reports, show reviews, and technical commentary are regarded as reliable primary historical sources, widely used by historians, collectors, and researchers to document the development of early motorcycles and motor sport.

Source: Official Cotton Motor Company catalogues and factory brochures.
Source: The Motor Cycle (United Kingdom)
Source: Motor Cycling (United Kingdom)
Source: Technical data concerning JAP, Blackburne, Villiers, Rudge Python, and Sturmey-Archer engines has been derived from:

- Period manufacturer literature

- Trade publications of the era

- Surviving engineering documentation and historical registries

Source: cybermotorcyle

COTTON, THE MOTORCYCLE MASTERPIECE ®

1935-1936 Official Model Range Overview

Sporting Blackburne model - engined mount - a 350cc overhead - valve

Model 9/JC – 349cc JAP

Model 9/J – 349cc JAP 2-Port

Model 29/J – 349cc JAP

Model 29/B – 349cc Blackburne

Model 25/J – 490cc JAP

Model 25/B – 496cc Blackburne

Model 26/J – 596cc JAP

Model 26/B – 596cc Blackburne

Cotton 1935 racer 350cc

Model 25/RP – Rudge Python 500cc 4-Valve

Model 29/B – Blackburne 350cc 2-Port

Model 25/B – Blackburne 500cc 2-Port

Model 25/SA – Sturmey-Archer 500cc 2-Port

Model 6/J – JAP 250cc OHV

Model 30/J – JAP 250cc OHV

Model 30/B – Blackburne 250cc OHV

Model 6/B – Blackburne 250cc OHV

Model 1/V – Villiers 148cc Two-Stroke

Model 2/V – Villiers 246cc Two-Stroke

Model 1/B – Blackburne 150cc Sloper

Model 1/J – JAP 150cc Sloper

Model 2/J – JAP 250cc Sloper

Model 2/JC – JAP 250cc Sloper (Competition Specification)

Model 7/J – JAP 350cc Sloper Super

Model 8/J – JAP 500cc Sloper Super

COTTON, THE MOTORCYCLE MASTERPIECE ®

1935-1936 Official Model Range Overview

Sporting Blackburne model - engined mount - a 350cc overhead - valve

Model 9/JC – 349cc JAP

Model 9/J – 349cc JAP 2-Port

Model 29/J – 349cc JAP

Model 29/B – 349cc Blackburne

Model 25/J – 490cc JAP

Model 25/B – 496cc Blackburne

Model 26/J – 596cc JAP

Model 26/B – 596cc Blackburne

Cotton 1935 racer 350cc

Model 25/RP – Rudge Python 500cc 4-Valve

Model 29/B – Blackburne 350cc 2-Port

Model 25/B – Blackburne 500cc 2-Port

Model 25/SA – Sturmey-Archer 500cc 2-Port

Model 6/J – JAP 250cc OHV

Model 30/J – JAP 250cc OHV

Model 30/B – Blackburne 250cc OHV

Model 6/B – Blackburne 250cc OHV

Model 1/V – Villiers 148cc Two-Stroke

Model 2/V – Villiers 246cc Two-Stroke

Model 1/B – Blackburne 150cc Sloper

Model 1/J – JAP 150cc Sloper

Model 2/J – JAP 250cc Sloper

Model 2/JC – JAP 250cc Sloper (Competition Specification)

Model 7/J – JAP 350cc Sloper Super

Model 8/J – JAP 500cc Sloper Super

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