Two-stroke

Alpha-Otto has a design that aims to eliminate the drawbacks of two-stroke engines. The RevForce engine introduces a single, transformative change to the conventional two-stroke layout that preserves its benefits while removing its major flaws.

He's an eccentric motorcycle and engine building genius who regularly creates mind-bending engineering alchemy and has millions of fans... So why is his extraordinary work so badly undervalued at auction? Someone's getting a bargain today.

Free goosebumps with every view. Watch as an original, complete, un-started HRC GP bike is uncrated. The bike has just become the most expensive Japanese motorcycle and the second-most-expensive two-stroke motorcycle in auction history.

We've seen some mad Hayabusa custom bikes over the years, but this one's right out of the box. It ditches the original engine for a massive two-stroke V6, but Meggatech Projects plans to make it look close to a standard Suzuki once it's finished.

Two-stroke streetbikes have never sold well at auction – but in the last few weeks, something strange has been happening. Kawasaki's Mach IV H2, the notorious 750cc "Widowmaker," is setting record prices after a flurry of sales to a single buyer.

According to the UN, there are about 258 million widows in the world. Tomasin Racing feels these are rookie numbers, so it's making a kit that turns a standard Honda CRF 450 into a certified widow production facility with a 500cc 2-stroke engine.

The road-going two-smoker ain't dead yet! Weighing in at an incredible 112 kg and bedecked in carbon and gold leaf, the Langen 2-Stroke is built around a screaming 80-horsepower fuel injected V-twin from Vins, and it's an absolute beauty.

British company Camcon Automotive has built a fully digital engine valve system, uncoupled from the crank, that offers unprecedented control over the combustion cycle. It enables some weird and wonderful ideas we've never seen before, such as giving 4-stroke engines brief 2-stroke power boosts​.

Italian manufacturer Vins is having an honest-to-god crack at getting a two-stroke 250cc roadbike back on the market, using a carbon frame and forks and some pretty wacky design to keep the weight down to a ridiculous 95 kg (209 lb). Oh, and there's a race version that's 10 percent lighter again.

KTM has unveiled a fuel injected two-stroke engine that is expected to give four-strokes a good run for their money. Available in 250 and 300 cc capacities, the new single-cylinder motor promises the best of both worlds, all the while satisfying the strictest emission standards.

​Despite the ever-tightening noose designed to legally choke emissions, KTM goes against the Euro 4 flow by announcing a new two-stroke platform for its Enduro motorcycles. And it could well prove to be a game changer.

With an electric motor and a two-stroke motor on each rotor, a quadcopter from German startup Yeair! is claimed to offer a full hour in the air, a top speed of 100 km/h (62 mph), and a fairly hefty 5 kg (11 lb) payload.