MotoSpecs

1966 AJS Model 31 650 vs 2026 Royal Enfield Bullet 650

Full specifications comparison • 2 motorcycles

Comparing 2 motorcycles
1966 AJS Model 31 650 1966 AJS Model 31 650

Classic

Engine
Four stroke, pushrod parallel twin, OHV, 2 valves per cylinder,
Power
31,4 kW / 43 hp @ 6000 rpm
Top Speed
N/A
Weight
176 kg / 388 lbs
2026 Royal Enfield Bullet 650 2026 Royal Enfield Bullet 650

Classic

Engine
Four stroke, parallel twin, SOHC
Power
34 kW / 46 hp @ 7250 rpm
Top Speed
N/A
Weight
243 kg / 536 lbs
Full Specifications
General
Year1957 - 662026
Make ModelAJS Model 31 650Royal Enfield Bullet 650
Dimensions
Seat Height-800 mm / 31.5 in
Wheelbase-1476 mm / 58.1 in
Ground Clearance-155 mm / 6.1 in
Height-1138 mm / 44.8 in
Length-2319 mm / 91.3 in
Width-892 mm / 35.1 in
Weights & Capacities
Dry Weight176 kg / 388 lbs243 kg / 536 lbs
Fuel Capacity16 L / 4.2 US gal14.8 Litres / 3.9 US gal
Performance
Max Power31,4 kW / 43 hp @ 6000 rpm34 kW / 46 hp @ 7250 rpm
Max Torque-51.5 Nm / 38 lb-ft @ 5650 rpm
Engine
Displacement646 cc / 39.4 cu in646 cc / 39.4 cu in
Engine DetailFour stroke, pushrod parallel twin, OHV, 2 valves per cylinder,Four stroke, parallel twin, SOHC
Bore x Stroke72 x 79.3 mm78 x 67.8mm
Compression Ratio7.5 : 19.5:1
Cooling SystemAir cooledAir/oil-cooled
Fuel InductionCarburetorBosch fuel injection
Ignition6 V (After 1964 12 V) Magnet (Lucas K2F) Digital electronic ignition
StarterKickElectric
Drivetrain
ClutchMulti Plate (dry, Burman)Wet, multiplate, slip and assist
Final DriveChainChain
Transmission / Drive4 Speed6 Speed, constant mesh
Chassis
Frame TypeSingle cradleSteel-tube spine
Suspension - FrontHydraulic telescopic fork43mm telescopic fork, non-adjustable
Suspension - RearDual chocksDual shocks, spring-preload adjustable
Wheel Travel - Front-119 mm / 4.7 in
Wheel Travel - Rear-89 mm / 3.5 in
Wheels & Brakes
Brakes - FrontDrumSingle floating disc, Ø 320 mm, 2 piston floating caliper
Brakes - RearDrumSingle disc, Ø 300 mm, single floating caliper
ABS-Two-channel
Tyres - Front3.25 -19100/90 -19 MRF NyloHigh-FN
Tyres - Rear3.50 -19140/70 -18 MRF NyloHigh-FN
WheelsSteel, wire spokesAluminium

Verdict

Winner on specs

2026 Royal Enfield Bullet 650

The 2026 Royal Enfield Bullet 650 edges out the 1966 AJS Model 31 650 thanks to its more peak power, fuel injection and standard ABS. Specifications are one part of the picture - dealer support, parts availability, and intended use all matter too.

Key Differences

1966 AJS Model 31 650 - Advantages

  • Lighter: 176 kg vs 243 kg - easier to handle and less fatiguing on long trips.

2026 Royal Enfield Bullet 650 - Advantages

  • More power: Produces 34 kW vs 31,4 kW - a meaningful performance advantage.
  • Fuel injection: Precise fuelling, better cold-start reliability, and lower maintenance requirements.
  • Standard ABS: A meaningful safety advantage in emergency braking on wet or loose surfaces.

1966 AJS Model 31 650 vs 2026 Royal Enfield Bullet 650 - FAQs

What are the engine differences between the 1966 AJS Model 31 650 and 2026 Royal Enfield Bullet 650?
The 1966 AJS Model 31 650 uses Four stroke, pushrod parallel twin, OHV, 2 valves per cylinder,, while the 2026 Royal Enfield Bullet 650 is powered by Four stroke, parallel twin, SOHC.
Which is lighter, the 1966 AJS Model 31 650 or the 2026 Royal Enfield Bullet 650?
The 1966 AJS Model 31 650 is lighter at 176 kg compared to 243 kg for the 2026 Royal Enfield Bullet 650 - a difference of 67 kg. This is a meaningful difference that affects handling and rider fatigue.
Which has more power, the 1966 AJS Model 31 650 or the 2026 Royal Enfield Bullet 650?
The 2026 Royal Enfield Bullet 650 produces more peak power at 34 kW, compared to 31,4 kW for the 1966 AJS Model 31 650.
Does the 1966 AJS Model 31 650 or 2026 Royal Enfield Bullet 650 have ABS?
The 2026 Royal Enfield Bullet 650 is listed with ABS as standard. The 1966 AJS Model 31 650 does not list ABS. ABS provides a meaningful safety benefit in emergency braking on wet or loose surfaces.
Which should I buy, the 1966 AJS Model 31 650 or the 2026 Royal Enfield Bullet 650?
Both are strong choices. The 1966 AJS Model 31 650 has the edge in lighter kerb weight, while the 2026 Royal Enfield Bullet 650 stands out for more peak power and fuel injection. Visit dealers, arrange test rides, and factor in local parts and service costs - these often matter as much as the spec sheet.

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