>>>    No way! 4-strokes machines also fires once per cilynder per revolution!!
>>>The difference is that 2-strokes combines the phases of Admission and
>>>Expansion in one stroke and Compression and Expulsion in other stroke!!! The
>>>spark plug fires everytime the motor hits the compression phase,
>>>independently of how many strokes your motor uses.
>>
>>>    Rafael Pinto
>>
>>Who told you this?
>>
>>A 4-stroke engine has (you guessed it) 4 strokes.
>>Intake, compression, ignition and exhaust.
>>
>>The complete prosess takes two revolutions of the engine. The spark plug
>>fires once in this period, ie every other revolution.
>>
>>Should be easy to understand?
>>
>>-Oyvind
>>
>>
>Your explanation of the four strokes is correct but the plug fires every
>revolution. The cam is ground onto the crank shaft and the points operate
>off the cam. The plug firing at the top of the exhaust stroke does not do
>anything to the operation of the engine but simplifies the design. There is
>a second geared cam that operates the valves to provide the 4 phases of
>operation. The electrical current is generated in the magneto coil by the
>magnet in the flywheel moving past the coil. This also happens once per
>revolution.

I merely stated the working principle of a 4-stroke engine.
No implementation details included.

If manufacturers can save money by firing the plug every revolution
that's fine. But it hasn't got anything to do with the working principle, nor 
performance.

But then we all agree on this subject and we can move on to another
 OT.....  :-)

-Oyvind