AJS 1927 H6 bigport
The 350 cc AJS OVV machines from the twenties got their nickname “bigport”from the enormous size of the exhaust port and pipe.
Between 1920 and 1922 AJS was very successful in racing with 350cc ohv machines; their catalogued models then were all side valve machines.
For the 1923 season the ohv concept was first used for customer models; its official name was the “2 ¾ hp three speed Overhead valve T.T. model” , but unofficially it immediately became the “Big Port”Ajay. From 1925 on prefixes were used to the numbering system:
E=1925, G=1926, H=1927 K= 1928.
Engine dimensions were 74×81, detachable cylinder head, three speed AJS countershaft gearbox., speed about 70 miles per hour, weight approximately 90 kilograms.
1927 was the last year of the “goalpost”setup to secure the cylinder&head to the crankcase.
New features for the year were among others a redesigned timing case to conceal the exhaust valve lifter mechanism, a roller bearing supported crankshaft and a new Pilgrom mechanical oil pump with sight feed.