The Yamaha TT 500 ruled the world before the YZ-F
There was a time that riding a four-stroke in motocross was considered being different or unique. Four-strokes were winning motocross races in Europe in the 1950s and part of the 1960s, but things changed around the late 60s and early 70s as light-weight two-strokes put thumpers out of business, or did they?. In the mid 1970s and early 1980s, the Yamaha TT 500 was a very popular recreation trail bike in the US and there were a slew of modifications to make improvements. In fact hop-up shop turned distributor White Brothers help put their name on the map with mods for this very bike.
Yet there were those who took the concept way further. There have always been the crazy-minded who would buy a bike and then proceed to replace nearly every part on the motorcycle except for maybe the engine cases. The TT 500 was essentially a made for the US market machine but that did not stop a few Europeans from getting a go on one. In 1975 four-time World Motocross champion Torsten Hallman and two-time World Motocross champion Sten Lundi wanted to see what they could do with the TT. Rumor has it they purchased their first bike, an XT500 off a rider that was at the Six Days because they were not available in Europe and Yamaha would not get them one.
From there the rest is history, the HL500 was born, or what call the Aberg 500. Hallman built a bike complete using a modified Yamaha TT 500 powerplant and virtually every other stock part was scrapped. In later years certain certain parts were available for purchase and all sorts of people build replicas of the Aberg. The engine was basically the only real components left on the HL 500. The original prototype frame was later sent to Pro-Fab to craft and build a production frame. The frames were later available so customers could build a kit bike as the years went on. Even Ricky Johnson raced a Pro-Tech TT 500 version at some of the first US four-stroke nationals in the early 80s.
The custom built TT 500 Motocross project bikes are still works of art to this day and a foreshadow to the changing of the guard years later. In the early 80s if you would have predicted that four-strokes would take over motocross, people would have thought you were smoking something. So if electric motocross bikes take over, what were you smoking?
