I believe this is for rigid competition because it is narrower than standard it is 3 and 1/8. The pipes are a bit crudely bent. There is no rust inside.
AJS Model 16 18 Motorcycle Manual 1956 Professional Reprint Book Large Format
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AJS Single twin Model 16 18 20 31 Parts Book 1959 Original Illustrated List
AJS 350 500 650 MODEL 16 18 20 31 ORIG. 1959 INSTRUCTION & MAINTENANCE HANDBOOK
4x Ewarts Petrol Tap Corks for AJS Ariel BSA Matchless Norton Triumph Villiers
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