6 out-there bikes you’ve probably forgotten

1. Harley-Davidson Cafe Racer
It was the late 1970s when Harley-Davidson's XLCR broke cover and was marketed by the Milwaukee firm as a high-performance motorcycle. Powered by the same 998cc pushrod engine as the XL Sportster and matched to a four-speed gearbox, it had a peak power output of 61hp at 6200rpm, it weighed nearly 250kg and it boasted a top speed of somewhere around 190km/h. Despite the American marque's high expectations, the model was only produced for two years (1977 and 1978) before it quietly disappeared off the production schedule.

2. MTT Y2K
If you've ever heard the Y2K jet bike running, then he chances are you'll probably never forget it. But if you haven't had the pleasure, then it's likely the headline-grabbing motorcycle isn't as vivid in your memory as it ought to be. The American firm, Marine Turbine Technology, thought it would be a good idea to take a gas turbine engine meant for a helicopter and slip it into a twin-spar aluminium chassis and turn it into a road-going machine. It pumped out an obscene 286hp, weighed less than 200kg and had an entirely believable top-speed claim of 400km/h. They were in production for four or five years and variants even appeared some years later. In fact, according to the company's website, they’re still in production, the current model called the 420 RR (Race Ready) Turbine Superbike.

3. Honda Valkyrie
It was the late 1990s when Honda decided the world needed a cruiser variant of its 1520cc flat-six Goldwing tourer. Between the Goldwing's popularity and the American market's growing interest in laid-back cruisers, the 1996 Honda Valkyrie hit the market with a clever and well-timed mix of both. It used a conventional tubular-steel chassis and, while it had decent ground clearance by cruiser standards, it carried all of its 310kg of heft low in the frame. Because of this, and just like its touring counterpart, it was often described as being surprisingly user-friendly.

4. Boss Hoss V8
I'll never forget the sight of Mick Matheson dropping off the gutter in Sydney's inner CBD on a 460-something kilogram Boss Hoss V8. It was powered by a so-called small-block 5735cc Chevrolet 90-degree V8 engine, capable of 345hp at just 5000rpm, and it was nothing short of outrageous. It’s the work of Tennessee-based Monty Warne, who surprised even himself when his out-there project started attracting interest from would-be owners. To date, well over 1000 examples of the Boss Hoss have been produced, the model even spawning a baby V6 version some years later, in 1996.

5. Yamaha GTS1000
Yamaha's 1993 GTS1000 was the first modern motorcycle to be mass produced without a conventional telescopic front fork. Using a single-sided swingarm type arrangement instead, Yamaha hoped separating the functions of suspension and steering would make for a stable and more appealing sportstourer. It was powered by a 1002cc variant of the firm’s FZR1000 engine, which was retuned for touring, and capable of 100hp at 9000rpm. Yamaha's brave move didn't live up to the Japanese firm's expectations, probably a result of its high price rather than its whacky front end, and apart from efforts by the odd boutique builder it's safe to say the front fork will be with us for a while to come.

6. Bimota HB2
No one ever wants to forget any Bimota, but if you were going to slip up just once, the HB2 might be to blame. Not least because its predecessor – the HB1 – was a game changer. Enormously advanced for its time, the Honda CB750-powered HB1 was both beautiful and rare, with only 10 examples ever produced. So when the CB900F-powered HB2 came along in numbers almost 20 times greater, it didn't quite attract the same attention. Though still beautiful, and still relatively rare, the HB2 broke cover in 1982, boasted 95hp and had a top-speed of 220km/h.