This comprehensive maintenance manual provides detailed instructions for servicing and repairing AJS Twin models manufactured between 1949 and 1955. Covering a wide range of topics, the manual equips owners and mechanics with the knowledge necessary to keep these classic motorcycles running smoothly.

Dive into the intricacies of the engine, from lubrication system maintenance and crankshaft sludge trap cleaning to head valve adjustment, ignition timing, and decarbonizing procedures. Learn how to remove and replace timing gears, troubleshoot engine noises, and perform a complete engine overhaul, including disassembly, inspection, reassembly, and balancing procedures.

The manual delves into the complexities of carburation, covering the workings of various carburetter types, troubleshooting common faults, and providing guidance on adjustments for optimal performance. Explore the nuances of transmission maintenance, including chain adjustment, lubrication, and gearbox servicing. Learn how to diagnose and address common gearbox faults, disassemble and reassemble C.P. and B.52 gearboxes, and troubleshoot clutch issues.

Gain insights into frame and fork maintenance, covering steering head adjustment, wheel alignment, teledraulic suspension troubleshooting, and detailed instructions for dismantling and servicing the front forks. Master the art of maintaining wheels and brakes, from adjusting wheel bearings to dismantling brake drums and replacing brake liners. Learn how to identify and remedy common brake issues, including squealing and ineffective braking.

The manual also provides an in-depth exploration of electrical and ignition systems, encompassing magneto lubrication and adjustment, dynamo testing and removal, regulator testing and cleaning, cut-out testing and adjustment, sparking-plug maintenance, and ammeter testing. Understand battery care, lamp bulb replacement, and headlamp adjustment.

Enhance your motorcycle's performance with the tuning section, offering guidance on valve timing, valve springs, rocker clearances, carburation optimization, exhaust system maintenance, and frame adjustments. Learn how to maximize performance by optimizing wheel and tire selection and chain adjustments.

The manual concludes with valuable appendices, including a periodic maintenance schedule, recommended lubricants, technical data, spring data, gearbox and chain data, and a comprehensive index for quick reference.

The AJS Twin Model S, produced from 1949 to 1955, was a revolutionary motorcycle that marked a significant shift in AJS's design philosophy. The "S" denoted "Sports," hinting at the machine's intended purpose. This motorcycle, powered by a 498cc parallel-twin engine, was a departure from the company's traditional single-cylinder offerings. The engine, featuring a robust cast iron construction with a 6.5:1 compression ratio, delivered impressive power for the era, generating 23 horsepower that allowed for a top speed of around 80 mph. The Twin Model S employed a four-speed gearbox with a chain drive, a setup common for the time. It boasted a rugged, durable frame constructed from robust steel tubing, ensuring a reliable and sturdy ride. The design was further enhanced by telescopic forks at the front and a swinging arm with twin shock absorbers at the rear, providing a smooth and comfortable ride.

The AJS Twin Model S was a popular choice for both enthusiasts and professional riders. It was lauded for its powerful performance, reliable engine, and sturdy construction, proving itself capable of handling both everyday commutes and demanding sporting events. However, the bike's weight, around 350 lbs, and the lack of a front brake (standard equipment was a rear-only brake) could prove challenging for certain riders, particularly those unfamiliar with the dynamics of a larger motorcycle. Nevertheless, the AJS Twin Model S stands as a testament to the company's engineering ingenuity and its commitment to providing riders with a powerful and well-built machine that redefined the motorcycle experience during the post-World War II era.