The Yamaha TZ125 is a two‑stroke, single‑cylinder racing motorcycle that was manufactured by the Japanese company Yamaha Motor Co., Ltd. for competition in the 125 cc Grand Prix class. It belongs to Yamaha’s “TZ” series of purpose‑built track motorcycles, which also included the TZ250, TZ350 and TZ500 models.
Overview
The TZ125 was introduced in the mid‑1970s as a successor to Yamaha’s earlier 125 cc race machines. It was designed specifically for road‑racing circuits and was not intended for street use. The motorcycle’s lightweight chassis, high‑revving engine, and compact dimensions made it a popular choice for privateer racers as well as factory‑supported teams in the 125 cc Grand Prix category.
Development and Production
- Initial release: The first TZ125 model appeared in 1975.
- Production span: Production continued, with periodic updates, through the early 1990s. Precise termination dates vary between sources; accurate information is not confirmed.
- Design philosophy: Yamaha emphasized a low centre of gravity, a narrow frame, and a high power‑to‑weight ratio. The bike’s engine was derived from Yamaha’s successful 125 cc two‑stroke road‑racing platform but was tuned for maximum output at high RPMs.
Technical specifications (representative of later models, e.g., 1983‑1990)
- Engine: Air‑cooled, two‑stroke, single‑cylinder; bore and stroke approximately 56 mm × 50 mm.
- Displacement: 124 cc (as per class regulations).
- Power output: Approximately 35 kW (≈ 47 hp) at 12,500 rpm, subject to variation by model year and tuning.
- Transmission: 12‑speed constant‑mesh gearbox, operated via a foot‑shift lever.
- Frame: Double‑cradle steel or, in later versions, aluminium alloy for reduced weight.
- Weight: Dry weight around 85 kg (187 lb).
- Fuel system: Carbureted with a reed‑valve induction system.
- Brakes: Front and rear single‑disc brakes, typically 260 mm in diameter.
Racing use
The TZ125 was widely employed in national and international 125 cc championships throughout the 1970s, 1980s, and early 1990s. It served as the basis for many riders’ entry into Grand Prix competition and was a common platform for private teams due to its relative affordability and ease of maintenance. Notable riders who achieved success on the TZ125 include several future World Champion riders during their early careers, though specific championship records vary by season.
Legacy
Although production ceased by the early 1990s, the Yamaha TZ125 remains a celebrated historic racing machine. Restored examples are frequently displayed at classic motorcycle events and are used in historic racing series that recreate the atmosphere of 125 cc Grand Prix racing from the era.
References
The information presented is derived from Yamaha’s historical model catalogues, contemporary race reports, and specialist publications on two‑stroke Grand Prix motorcycles. Where precise production dates or specifications differ among sources, the most widely accepted data have been used. Accurate information is not confirmed for certain production year details.