Cotton Conquest. 1965.

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13. Cotton Conquest / 1965

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  • By a cool six mph, the Cotton “Conquest” which Derek Minter and Peter Inchley took to a class victory in the 1965 500-mile race at Castle Combe, becomes the fastest 250cc we have ever tested.
  • It averaged 91.9 mph round the 3-mile banked circuit of MIRA’S proving ground

Previous best was the 86.0 mph of the Honda “Dream SS’. However, this “Conquest” is a road-going racer, with questionable silencing and primitive lights.

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High Compression

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It is basically a standard “Conquest” as turned out by the Gloucester factory, but with the compression ratio increased from 10 : 1 to 12 : 1.

  • The test “Conquest” had bobby-dodger items such as feeble, direct lighting, in place of the standard Lucas diode lighting, and a bulb horn. Shod with racing tyres, it lacked centre or prop stands.
  • It cannot be put into the same élan’s as the fully equipped and well-silenced 250 Honda. In fact, the Minter / lnchley “Conquest” is in a class of its own. Orders for exact replicas have already been placed at a provisional price of £370, including Purchase Tax.
  • Torque characteristics
  • Tuned to give rising torque all the way, the Villiers “Starmaker” two-stroke single always reached maximum revs on any up-gradient which it was able to climb in top gear.
  • This gave it a shattering motorway performance, leaving behind on the hills much faster cars capable of cruising at 140 mph and more, on level roads.
  • The Cotton climbed such hills at 85 to 90mph. It was cruised at full bore by the simple expedient of putting the throttle against the stop and leaving it there, from London to the Midlands and returns, except past motorway roadworks. This is a race engine, designed to run at maximum effort, and it thrives on it.

On downgrades the speedometer rose to flicker around the 114 to 116 mph mark, if the rider got his head down. This, after speedometer correction, would suggest a true 105 mph.

Owing to the engine’s unusual characteristic of rising torque up to peak rpm of 8,000, the machine was faster on a windswept lap at MIRA than it was through the one-way timing traps, the first time we have ever experienced this.

This feature makes the engine rush up the power band once about 5,400 had been reached.

The acceleration was then staggering.


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Megaphonitis

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Below this speed, and especially under 3,500 rpm, bad four-stroking set in, the rate of rev rise, even in a low gear, was poor, calling for much use of the gearbox to affect a cure. 


Flywheel weight was negligible. This, the lack of low-down urge, the exhaust note, made traffic riding grim. The Cotton needed a softer plug in London, and changing a plug meant some five minutes fiddling under the tank.  

By no stretch of the imagination can the Minter / Inchley device be regarded as daily transport. It is in its element on the open road – and only on the open road.

The motor was then untirable, free from vibration, and no thirstier than about 45 mpg. The fuel tank holds five gallons, which is mixed with R oil at 16 : 1.

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Starting was infallible, Idling was a lumpy 2,200 rpm with the engine nagging to be given the gun, It is a motor that has to be let off the leash – and then it’s tops.

Matching the power plant, in its high-speed excellence, the Villiers four-speed gearbox had an ultra-fast action.

When the bike was in full flight instantaneous 2-3 and 3-4 changes could be made clutchless at 7,500 rpm by simply easing the grip and lifting the reversed pedal,

Clutch action was reliable but heavy. Although the clutch was slip-proof for one full-bore take-off it needed time to cool before the treatment could be repeated.

Precise and confidence breeding, the navigation became its very best, when the tester slid well back on the racing seat.

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Handling was then noticeably improved, without fear of front-end lightness or of either wheel stepping out.

Cornering clearance to the left was fair. To the right, it was magnificent.

On the straight, over roughish roads taken at high speeds, the bike held the line but some mild twitching from the Armstrong front forks set in going over an un-level railway crossing on the A5 at 80 mph.

This twitch, which always appears on racing Cottons over a certain type of bump, never worsens and is predictable, as well as controllable. Suspension was firm, almost hard at town speeds. On the open road, it was splendidly damped as befits race-bred springing.  

Braking was progressive and powerful. The front unit was man enough to provoke loud tyre squeal at 70 or more mph. nothing else could be expected from racing stoppers anyway.

The tacho drive is taken direct from the Starmaker crankshaft. The cable into the top of the chaincase controls the diaphragm clutch. The 7″- inch brake on the British Hub wheel has two leading shoes and a parallelogram reaction linkage. Crank in the folding kickstart to clear the reversed gear pedal, which has up-for-up action.

It has the distinctive finning of the later type Starmaker, whose central exhaust port imposes severe frame constraints. 

Conforming to road and race regulations, but expressly tailored for one particular event, the Minter / lnchley Cotton Conquest is a magnificent highway burner to take out into the country for the sheer zest of motorcycling.

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