Diesel motorcycles are extremely rare nowadays. They are mostly being used by the military and enthusiasts, who want to install a diesel power plant instead of fuel engine.

Certainly, a diesel engine has a number of benefits over the fuel one. It’s the relative simplicity of use and low service intervals (we are talking about the simplest “diesels”, not about super-advanced ecological engines in modern vehicles), and its unpretentiousness to the fuel quality. It concerns big engines, used in industrial equipment such as locomotives, ships, trucks and also electricity generations.

Nevertheless, the above reasons are fair, if we talk about big engines. If the size of a diesel engine is reduced, all benefits will be ruined. The main issue concerns about the high compression ratio. The compression ratio of typical fuel engines are about 10:1 – it depends on a producer, while the compression ratio of diesel engines are in the range of 18:1 to even 20:1. That much higher compression ratio is needed to cause the fuel/air mix to ignite without the need for a spark plug.

Due to the above reasons the engine block must be made stronger to withstand high compression ratios and high detonation force. Plus the transmission also needs to be specially constructed because of the different forces that engine will impose on it. Don’t forget, that diesel engines create more torque than their fuel counterpart, what increase the weight of the engine. So why would anyone want to install a heavier diesel engine in a light-weight motorcycle?

There are some reasons:

• need of using of tacky fuel, such as diesel distillate or aviation kerosene;
• need for high fuel economy and the extended range it provides;
• need for high reliability.

Not everyone and not everywhere wants a high-speed motorcycle, sometimes a racing range and simplicity become the priority. The diesel motorbikes are often used in agriculture, and in places, where there is no high-quality fuel basically. And don’t forget about the military – they have only one kind of fuel for all types of equipment: aircraft, armoured vehicles, motorcycles and trucks.

The first documented fact of using a diesel engine in a bike came under 1904 and it’s connected with the name of Dutchman Jan Dopper. Exactly that man installed the “diesel” Brons into a bicycle, which he’d got also in 1904. That engine produced 2 hp at 700 rpm. Dopper improved it by creating a new frame, and then in 1910 he presented the first diesel tricycle.

In post-war Britain the Norton company was tried to produce diesel powered motorcycles. The first Englishman to build a diesel motorcycle was Tony Sidney, who created a 500cc aluminium single cylinder engine with a cast iron head and fitted it into a Norton.

The use of aluminium helped keep the engine lightweight. It produced 10-14hp at 4000 & rpm. A top speed of that commuter was 89 km/h, and the bike was very capable climbing hills. But the main issue was slow and weak acceleration. The bike gained momentum, but it was of little value. Besides, the motorcycle needed to be push started in cold weather.

The similar motorcycle was built by Freeman Sanders, whose Norton engine produced 18.8 hp at 4500 rpm giving the bike a top speed about 113 km/h and miserly fuel consumption of around 2Lt/100 km. It’s interesting, that Sanders modified the bike just a little. He changed the construction of a 490cc one-cylinder engine and, as a result, he kept the compression ratio down to 11.8:1. Despite the success, his motorcycle did not get past the prototype stage.

The first company, which started to sell diesel-powered engines, was Royal Enfield – a famous even nowadays Anglo-Indian company. Its bikes are said to be “Built like a gun, fast as a bullet”. But it was certainly no “bullet”. Nowadays the most famous of their diesel-powered projects is Taurus. It is a modified version of Royal Enfield Bullet, made by Sooraj Automobiles.

The company began installing Greaves Lombardini diesel engines in stock Royal Enfield Bullet motorcycles. It was sold through the established Royal Enfield dealer network and widely used in agriculture and governmental institutions.

Currently diesel motorcycles are being mass produced by Hayes Diversified Technologies, mostly for military use. The most popular HDT M1030M1 is based on Kawasaki KLR650, which is fitted with a 584cc diesel engine instead of the fuel one and boasts a top speed of 145 km/h. Fuel consumption is 2.45Lt/100 km.

The bike is already being supplied to the US Marine Corps, Britain and NATO. It also has a civilian version, but it is not available yet.

There are also other well-known customs, which are worth to be mentioned:

Star Twin Thunder Star 1 200 TDI, which is fitted with a three cylinder Volkswagen Lupo 1.2 Lt diesel engine, producing 91 hp. It’s modified with a custom crankcase and mated to a five speed gearbox.

Neander Motors: This prototype bike was unveiled in 2005 and presented under “The world's first turbo diesel motorcycle”. The Neander is fitted with the engine power rated at 113 hp at 4200 rpm, and its top speed is 220 km/h. Unfortunately Neander didn’t get past the prototype stage.

Russian motorcycle manufacturer Dnepr also makes an importing diesel model, but due to high fuel consumption and ecological-standard mismatch, it’s not available everywhere. And the motorcycle isn’t super popular, where you can get it.

#Moto #Bike #Custom