AJS H6 Big Port


Make Model.

AJS H6 Big Port 350




Single cylinder, 4-stroke, OHV


349 cc / 21.3 cu in
Bore x Stroke 74 x 81 mm
Compression Ratio 7:1
Cooling System Air cooled
Exhaust 1-into-1
Starting Kick

Max Power

2.0 kW / 2.75 hp


3-Speed, countershaft
Final Drive Chain

Front Suspension

Girder fork

Rear Suspension

Rigid, springloaded saddle

Front Brakes


Rear Brakes

Wheels Steel, wire spokes
Dry Weight 90 kg / 198 lbs
Fuel Capacity 15.9 L / 4.2 US gal
Top Speed 130 km/h / 81 mph

After victory in the 1920 Junior TT, AJS's new overhead-valve 350 racer scored a memorable double the following year, Tom Sheard winning the Junior race, and Howard Davies the Senior - the first time such a feat had been achieved on a 350.

The production version made its debut in November 1922, delighting clubmen everywhere with its 'racer on the road' performance. A right-first-time design destined to achieve countless successes in the hands of privateers, the overhead-valve 350 AJS - latterly known as the 'Big Port' - changed only in detail before being superseded by a much-revised M6 model for 1929. The latter's engine incorporated a number of improvements including enclosed rocker gear and dry-sump lubrication, while the frame was redesigned to accommodate a saddle tank, and Webb forks replaced the earlier Druids.