A 4 stroke bike

How the Engines Work

“Stroke” is infact the movement of the piston in the engine.

Two Stroke means one stroke in each direction. A two stoke engine will have a compression stroke followed by an explosion of the compressed fuel. On the return stroke new fuel mixture is inserted into the cylinder.

A four stroke engine has 1 compression stroke and 1 exhaust stoke. Each is followed by a return stroke. The compression stroke compresses the fuel air mixture prior to the gas explosion. The exhaust stroke simply pushes the burnt gases out the exhaust.

Following is the comparison between the Advantages and Disadvantages of a two stroke engine.

Advantages of 2 Stroke Engines:
– Two-stroke engines do not have valves, simplifying their construction.
– Two-stroke engines fire once every revolution (four-stroke engines fire once every other revolution). This gives two-stroke engines a significant power boost.
– Two-stroke engines are lighter, and cost less to manufacture.
– Two-stroke engines have the potential for about twice the power in the same size because there are twice as many power strokes per revolution.

Disadvantages of 2 Stroke Engines:
– Two-stroke engines don’t live as long as four-stroke engines. The lack of a dedicated lubrication system means that the parts of a two-stroke engine wear-out faster. Two-stroke engines require a mix of oil in with the gas to lubricate the crankshaft, connecting rod and cylinder walls.
– Two-stroke oil can be expensive. Mixing ratio is about 4 ounces per gallon of gas: burning about a gallon of oil every 1,000 miles.
– Two-stroke engines do not use fuel efficiently, yielding fewer miles per gallon.
– Two-stroke engines produce more pollution.
— The combustion of the oil in the gas. The oil makes all two-stroke engines smoky to some extent, and a badly worn two-stroke engine can emit more oily smoke.
— Each time a new mix of air/fuel is loaded into the combustion chamber, part of it leaks out through the exhaust port.

 Ref: imascientist

So Which is Better?

At the end of the day the winner is probably going to be the one that has had more money and technology spent on it. In these days of quick and cheap international production schedules you can’t take it for granted that the 4 stroke will be better. So for your particular application, line up the options and make a decision based on what’s available, not based on lists that miss the key points of difference.

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