My father had a 2 stroke bike Escorts ' Rajdoot '. 2 weeks back sold it. It lasted for 18 years with very few maintenance, was very good for rough roads. The only problem was it was creating noise and black smoke, may be the reason to be forgotten.

Mr Sandeep,

I agree that there are problems. But the simplicity of this engine compensates an effort to improve it, is not it?

PS I particularly like the noise in a car with two-stroke engine. In bikes is always different!

I believe in the near next future all research programs will be inspired only towards hybrids engines or electrical engines. How do you think about?

Two stroke engines are not necessarily inefficient. I've worked with both crank scavenged and turbo scavenged engines in petrol and diesel. My impression of the large two stroke diesels were that they were pretty much on par with it's four stroke cousins, except that they were more compact.

Two stroke egines generally have higher power to mass ratios than four stroke. If mass is a critical factor, then efficiency is of less improtance.

What is true of crank scavenged two stroke machines is that lubricating oil is added to the fuel with, consequently, more visible smoke. This is because they operate with a dry sump. In contrast, turbo- or mechanically scavenged machines can have oil in their sumps (depending on the design), similar to four stroke machines and no need for lubricant in the fuel and the increased visible pollution.

Two stroke machines have a limited power band (speed range) where it is efficient and works just fine for generation applications.

Mr Amirante,

I agree. But I presented this question because the automotive industry is very slow in presenting innovations. Some aircraft in World War II were already using fuel injection, which became universal in cars only in the 90s.

Before we had the best car, I believe we need an intermediate generation.

Mr Johnson,

I agree. The two-stroke engines have several advantages. And the disadvantages can be overcome.

The two-stroke engines should be small? But ... we really need big engines?

I believe we have sports cars with big engines, but these engines can be hybrid engines.

they still have advantages in comparison with 4-stroke ones, you know the pulse is more similar to a rotary engine which wastes less energy, but they also have their own problems which should be discussed on, but maybe it's better to improve rotary engines rather than two-stroke engines, but if you consider the external combustion engine of Stirling it might be a good work as well.

I think the main consideration in 2-strokes is controlling emissions. First you need to avoid raw fuel going out the exhaust during the "cross flow" period. This means direct injection of fuel after the ports are closed, so either use diesel or gasoline direct injection. To avoid oil in the air/fuel mixture, it means using a positive displacement pump, like the Detroit Diesel did, not crankcase scavenging.

Unfortunately by the time you add all this, to improve emissions (and the bad smell), the 2-stroke is not so cheap and simple any more.

Indeed these days two stroke engines are less used as commercial vechile engine except motor, but for large power equipment, e.g. most of large and huge tonne vessel consider two stroke mairne engine as propusion power, for its large power output than four stroke.

for the more new control strategies and material used in two stroke engine, the emisiion will be reduced and will be fit for commercial vechile,

I think that the most important problem from the two stroke engines are the emissions. NOx, SOx and Particulate Matter etc, are emitted by two stroke engines but the problem is not the engine. The problem is the fuel. Nowadays, big engines are used for propulsion of ships (more than 30 MW) but they use gas as fuel. SOx and PM practically are eliminated and NOx are reduced by the use of this type of fuel

NO - Achates Power in San Diego California has an opposed piston, two-stroke, diesel, truck (reads "big") engine which they are claiming to be both more efficient and produce less emissions than current state of the art. I wouldn't discard the technology just yet.

I always believe no one technology that is better or worse. There is strategy and different applications.

Hello, I would be very interested in the latest industrial progress concerning two-stroke engines. We want to evaluate the 2-stroke engine for stationary applications. It would be great if you could supply some literature on the topic.

Thank you

hello, the two-stroke engines (Otto cycle,small swept volume) require a major effort in the design of fuel supply systems, such as direct injection into the combustion chamber. This is not new, several motorcycle companies have tried,  but results still unconvincing. The time available for injection is much less than a four-stroke engine, the fuel must be injected after the closing of the exhaust orifice. This is a very short space of stroke piston,in the less swept volume engines the jet fuel hits the walls and  partially preventing evaporation. A possible solution  to be a injector with compressed air assisted,  provided by the engine itself.