The Future Is Bright For Two Strokes
by Oliver Jenner
Although the modern trend is towards 4 strokes, modern developments in 2 stroke design sheds light on their future use.
One of the main problems with 2-strokes is their emissions in comparison to 4-strokes. Emissions are something which won't concern many dirt bike riders, however it concerns legislation in the automotive world and therefore it has a massive impact on research and development.
If the charge losses and emissions can be severely reduced along with the poor lubrication 2-strokes suffer, then they would have a sudden advantage over 4-strokes. This is due to their increased mean power output per revolution and their lower weight.
This equals performance which is good to car manufacturers who want lower emission vehicles, and is music to racers who thrive performance.
The good news to conclude this is that recent developments to solve the problems of two strokes have been happening. A good example is Lotus's 'Omnivore' concept engine.
The use of direct injection and poppet exhaust valves severely reduces the lost charge when both exhaust and intake ports are normally exposed. Wet sump lubrication increases engine life and severely reduces emissions. This reduces the maintenance cost by using far less oil and increasing engine component life.
If manufacturers pick up on the possibility of more fuel efficient 2-stroke engines before alternative fuels dominate the internal combustion engine, then we could possibly see high performance 2-stroke dirt bikes return in favour. Now that would make me happy!