The 1976 Yamaha’s new TT500 was Overweight and had poor geometry to compete against the stiff 500cc world competition, but did not deter a Swedish engineer and former double world champion (1959 and 1961) Sten Lundin. Lundin saw the potential of four-stroke Yamaha engine and at the end of the year bought a former prototype XT500 for International Six Days Enduro competition, and Immediately began his own project fitting the Yamaha engine into a Husqvarna frame.
It was January 1977 when Bengt Aberg first tested the new bike and immediately fell in love with it. The motorcycle was then sent to the U.S., where he specialized company ProFab built new lightweight chassis, while Aberg was testing in the U.S. carburetors, cams and dampers.
Yamaha is about to introduce the production model XT500 in Europe and realized that the glory acquired in international motocross is a great asset to marketing and sales . So in early 1977, when Lundin and Hallman asked Yamaha for support, to finance the participation in the GP with this hybrid motorcycle. It was decided that Aberg take part in the 500cc class with support from the Swedish importer of Yamaha Hallman, and one of Enqvist Hallmanových business partners, and also with Yamaha Europe. While the Swedes saw, a great potential in the competitive four-stroke motorcycle, Hallman explained the significance of potential managers Yamaha HL 500 victories in at least one Grand Prix the following year for the PR model XT.
Motorcycle design quickly evolved from chassis originally used by Husqvarna ProFab specialized company that developed a new lightweight frame that was to become the basis for a limited production model Yamaha. In collaboration with business partner Torsten Hallman, used Lundin ProFab parts such as frames and other stands on its own project, and therefore always had confidence in the Californian specialist firm producing high quality lightweight racing parts, which had an excellent reputation. New Hallman – Lundin Yamaha 500 project quickly developed the specification, which includes an aluminum swingarm and advanced air dampers Fox Air Shox. The initial letters of the names and Hallman Lundin figured now officially in the name of a motorcycle HL500.
At the end of 1977, further developed the original version. Were used lightweight hubs, forks twin engine mounts and other material for mounting the engine YZ production models. With only 225 dry weight the 500 HL was 45 lbs lighter than the TT500, and had a 250 mm travel suspension front and rear. Lundin then turned to the Swedish tuning ace Nils Hedlund, who modified the engine, the bottom drive unit which was tough enough was left untouched.
Aberg HL 500 won the Luxembourg Grand Prix, and the media soon earned the nickname Aberg Yamaha, Bengt Aberg completed a lackluster season after winning the Grand Prix of Luxembourg. Yamaha decided to abandon the project and not to support a future four stroke team, even during the 1978 season Aberg experimented with its HL500 and continued world competition. The machine, however, attracted the attention of European heads of Yamaha, who have decided to create a small production run of replicas HL500.
Although they lacked true winning power, total 200 pieces left the factory doors in the first year of production. The following year Yamaha made some changes to it’s production run, thy had a modified cams, enhanced CDI ignition and 38 millimeter Mikuni carburetor. Minor changes to the rear swingarm Rear wheel travel increased to 250 mm while the front fork used on Yamaha 400 F had a stroke of 267 mm.
European production was increased by 400 units, with additional machines manufactured by other markets specialists to build frames. Many of them have either inspired or heritage from the Aberg HL On the race track, these bikes were often the same or even better level than production machines , but few of them are now valued as high as Norton-produced models.
