Back to Bike FinderYears: 1953 · 1952 · 1951 · 1950 · 1949
Ariel 4G Square Four Mark I
1950Allround

Ariel 4G Square Four Mark I

Key specifications

Engine
995 cc
Power
35 HP
Weight
197 kg
Fuel type
petrol
Fuel capacity
4.2 L
Transmission
4-speed
Front brakes
Expanding brake (drum brake)
Rear brakes
Expanding brake (drum brake)

Overview

Introducing the 1950 Ariel 4G Square Four Mark I, a fascinating piece of motorcycle history that stands out in the allround category. Renowned as the "Squariel," this motorcycle is an expression of engineering brilliance, designed by the legendary Edward Turner. With its unique square four-cylinder engine, the 4G Square Four Mark I represents a harmonious blend of performance and elegance that appeals to both enthusiasts and collectors alike. Its striking red and silver color scheme, combined with a classic aesthetic, makes it an alluring option for those seeking a vintage ride that commands attention on the road. At the heart of the 1950 Ariel 4G Square Four is its impressive 995cc engine, which delivers a robust 35 horsepower at 5500 RPM. This power enables the motorcycle to reach a top speed of 90 mph (144.8 km/h), offering riders a thrilling experience on both city streets and open highways. The engine's square configuration not only enhances stability but also provides a remarkable smoothness in operation, making it a pleasure to ride. With a 4-speed gearbox and a chain final drive, the Square Four balances acceleration and cruising effortlessly, making it ideal for all-around use. The engineering marvel of the 4G Square Four doesn't stop with its engine. Its tubular single-loop frame ensures a sturdy ride, while the oil-damped telescopic front suspension and plunger-link rear suspension work in tandem to absorb bumps in the road, providing comfort and control. The braking system features expanding drum brakes both front and rear, with an 8-inch front diameter for effective stopping power. With a fuel capacity of 16 liters (4.23 gallons), the motorcycle offers respectable range, making it suitable for longer journeys. **

Pros

  • Unique Engine Design: The square four-cylinder configuration delivers smooth power and enhances stability, setting it apart from traditional parallel twins or V-twins.
  • Comfortable Ride: The advanced suspension system ensures a smooth and enjoyable ride, even on less-than-perfect roads.
  • Timeless Aesthetic: With its classic styling and striking color options, the 4G Square Four is a head-turner and a true collector's item.

Cons

  • Weight: At 197 kg (434.3 lbs), the bike may feel heavy for new riders and can be cumbersome at low speeds.
  • Limited Braking Technology: The drum brake system, while effective for its time, lacks the stopping power and modulation of modern disc brakes.
  • Kick Start Only: The absence of an electric starter means riders must rely on traditional kick-starting, which may be less convenient for some.

Technical details

Source specification data

Make
Ariel
Model
4G Square Four Mark I
Category
Allround
Light
30 Watt headlamp.
Starter
Kick
Comments
Also
called ´
Squariel
´.
Designed
by
Edward Turner
.
Color Options
Red/silver
Power
35.00 HP (25.5 kW)) @ 5500 RPM
Gearbox
4-speed
Top Speed
144.8 km/h (90.0 mph)
Engine Type
Double twin cylinder arranged as a square.
Fuel System
Carburettor. SU MC2 carburettor
Bore X Stroke
65.0 x 78.0 mm (2.6 x 3.1 inches)
Compression
6.0:1
Displacement
995.00 ccm (60.71 cubic inches)
Cooling System
Air
Engine Details
Square four cylinder
Exhaust System
Dual two-into-one
Lubrication System
Dry sump with dual oil pump.
Valves Per Cylinder
2
Transmission Type Final Drive
Chain
Dry Weight
197.0 kg (434.3 pounds)
Fuel Capacity
16.00 litres (4.23 gallons)
Overall Length
2,083 mm (82.0 inches)
Power Weight Ratio
0.1777 HP/kg
Seat
Solo seat
Wheels
Wire spoked
Rear Tyre
4.00-18
Frame Type
Tubular single loop
Front Tyre
3.25-19
Rear Brakes
Expanding brake (drum brake)
Front Brakes
Expanding brake (drum brake)
Rear Suspension
Plunger-link spring
Front Suspension
Oil damped telescopic
Rear Brakes Diameter
178 mm (7.0 inches)
Front Brakes Diameter
203 mm (8.0 inches)

Available colors

Red/silver