four-stroke engine
four-stroke internal-combustion engine

The special thing about the engine is that it weighs 40% less than other four-stroke engines.

Otto cycle is exactly the same one that was described for the four-stroke engine.

Up through the 1950s and most of the 1960s, four-stroke engines dominated all classes.

The first cars were two-stroke, with later use of a four-stroke engine, from 1967.

They also say that the industry is moving toward four-stroke engines, similar to those used in cars.

They also were powered with four-stroke engines of his own design.

If the tool has a four-stroke engine, changing the oil is important.

What is the difference between a two-stroke and a four-stroke engine?

They featured four-stroke engines of 198cc, 247cc and 249cc capacity.

This is the reason why they are switching over to four-stroke engines, which raise a different problem.