1Denoting an internal combustion engine having a cycle of four strokes (intake, compression, combustion, and exhaust). Compare with two-stroke.
- Unlike two-stroke engines that have simple openings or ports for intake and exhaust, four-stroke engines have intake and exhaust valves at each cylinder head.
- The combustion chamber of a four-stroke engine is designed to induce turbulence through the addition of ‘squish’ areas in which the top of the piston is the mirror image of a corresponding area of the cylinder head.
- In four-stroke engines, one of the strokes is called the compression stroke.
1.1Denoting a vehicle having a four-stroke engine.
- Two-stroke motorcycles should pay more pollution tax than four-stroke motorcycles and Euro2 compliant cars should pay no taxes at all.
- The race was split into four categories 50 cc, four-stroke motorcycles up to 180 cc, novice riders on two-stroke bikes and 100 to 135 cc for the experienced.
- If achieved, this expedition will ensure the entry of the team - riding Fiero FX 150 cc four-stroke power bikes - in the Guinness Book of World Records.
A four-stroke engine or vehicle.
- It weighs just slightly more than a comparable two stroke, a major break-through because just a few years ago, marine techies said four-strokes were unlikely to ever go higher than 100 hp.
- I've just bought a Honda four-stroke, the Rolls Royce of mowers.
- On the other hand, four-strokes are generally suited to applications appropriate to the lower horsepower range.
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