Bill,
I made myself curious by thinking about what I wrote earlier <g>. So I
went to the basement and dug out the service manual for my KZ650. It
turns out the '78 model KZ650 has a valve overlap of 42 degrees. On the
exhaust stroke the exhaust valve is open and the intake valve starts to
open at 22 degrees before top dead center. On the intake stroke the
exhaust valve doesn't completely close until 20 degrees after top dead
center. I'd bet your KZ750 is pretty close to being the same.
Rick
> Rick Fisk wrote:
>
>> Bill,
>>
>> The exhaust cycle and intake cycle in a typical four stroke engine
>> are _not_
>> mutually exclusive. There is a period of valve overlap - when the
>> exhaust valve
>> is closing the intake valve is partially open. This causes a
>> scavanging
>> effect. The exhaust gases flowing out help draw the fresh fuel/air
>> mixture in.
>>
>> Each cylinder in your motor is 187.5 cc's (plus the volume of the
>> combustion
>> chamber), but because of inefficiencies in the intake and exhaust
>> system you
>> don't get a full exchange of 187.5 cc's with every intake/exhaust
>> cycle. By
>> improving the flow of the exhaust system on your engine, you have
>> improved the
>> efficiency. You have more air flowing through your engine.
>>
>> Rick
>>
>
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