When Triumph announced the ‘Speed Twin’ in 1938 AMC (Associated Motor Cycles) knew they needed a twin for their AJS and Matchless lines. Though development started almost immediately, WWII pushed the introduction to 1948 for the AJS Model 20 and the Matchless G9.
AMC improved on the Triumph design in several ways, not the least of which was a third main bearing on the crank which helped significantly with longevity and power development. The AMC design started with a swing arm rear suspension and telescopic front that improved handling and ride.
The AJS Model 20 and the Matchless G9 were mechanically nearly identical with badging, trim and paint being the main differences.
The 1955 AJS Model 20 used a 498 CC air cooled four stroke overhead valve parallel twin motor that produced 33 HP with a 4 speed Burman transmission for a top speed around 85 MPH. Swing arm rear suspension with dual ‘Jam Pot’ shocks, telescopic front suspension and 7 inch drum brakes on a pair of 19 inch wheels completed the setup.
This particular 1955 AJS Model 20 (VIN #5520B23730) is in Ojai, California at Bator International and is listed as a ‘fully restored one owner bike that is ready for show or go.’ There isn’t much information in the listing, but the detail photos are very nice. 13 bids have taken the current price to $4,050.00 with reserve not met
Sources:
Wikipedia
Real Classic
Autorevolution
Classic British Motorcycles