Friday, September 21, 2007

Fearsome: The 1975 Yamaha TZ750 dirt-tracker

The TZ750 dirt-tracker had a 750cc, two-stroke engine that made 120bhp. And no front brakes!

You’ll often hear that the 1970s and 80s 500cc GP racing bikes were ‘evil’ and extremely difficult to ride. And indeed, they must have been that way. But even more than those GP bikes, it was perhaps the 1975 Yamaha TZ750 dirt-tracker, which the most ‘evil,’ most terrifying competition bike ever built. The TZ750 dirt-tracker was powered by Yamaha’s liquid-cooled, four-cylinder, 750cc two-stroke engine that made about 125 horsepower. Oh, and no brakes at the front…

Before he won successive 500cc road racing world championships in 1978, 79 and 80, ‘King’ Kenny Roberts was dirt-track racing in the US. Riding for Yamaha, he won the dirt-track AMA Grand National Championship in 1973 and 74, despite his bike being less powerful than the competing Harley-Davidson XR750 machines. Roberts made up for that power deficit by riding harder than everybody else, which made for some spectacular racing on the dirt ovals of America.

Says Kenny Roberts about the TZ750 dirt-tracker, 'You had to throw it sideways at 150mph [240km/h] to get it slowed for corners...'

In 1975, Yamaha tried to find a solution to their power deficit and fitted their dirt-tracker with the 120 horsepower engine from their TZ750 roadracer. The result was a monstrous, nearly uncontrollable machine. However, in August 1975, Roberts rode this TZ750 dirt-tracker at the famous Indy Mile dirt-track oval, winning the race ahead of Jay Springsteen and Corky Kenner.

He later admitted that the TZ750 dirt-tracker, which could hit speeds of up to 240km/h on the straights, was too scary even for him. ‘They don’t pay me enough to ride that thing,’ said King Kenny, and within a few weeks, the AMA went on to ban the TZ750 engine from dirt-track racing – that was the end of the machine’s short-lived dirt-track career.

The TZ750 dirt-tracker only won one race in 1975, but will still be remembered forever

Today, how does Roberts remember his old steed? Says The King, ‘You had to throw it sideways to get it slowed for the corners. There weren’t a lot of riders who could throw it sideways at 240km/h.’ Amen…

Also see:
The MotoGP-powered KRV5 board-tracker...
Superb: The 2008 Harley-Davidson XR1200!
Memorable: The mighty Yamaha YZR500...
Memorable: The Yamaha RD500LC
Face off: 1989 Yamaha FZR750RR vs 2008 Yamaha R1!
Bikes & babes: Hi-res wallpaper...
2007 MotoGP race reports, features, interviews and hi-res wallpaper
Are electronics ruining MotoGP...?
Team Kenny Roberts to leave MotoGP, go to World Superbikes in 2008

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