Noise and Hearing (was Re: [rescue] Re: Throw anotherpacket on the server...)

Curtis H. Wilbar Jr. rescue at
Sun Aug 24 14:18:39 CDT 2003

>From: Phil Stracchino <alaric at>
>On Sun, Aug 24, 2003 at 07:09:56AM -0700, Lionel Peterson wrote:
>> --- Ross Alexander <ross at> wrote:
>> > The firing strokes on all the big British twins that I know of are
>> > 360 degrees apart.
>> And the difference between 0 degree and 360 degree is, what? (Not
>> TRYING to be a pain, but from a non-motorcycle perspective, that sounds
>> a bit odd)
>> Thanks,
>OK.  Here's a simple capsule explanation:
>In a four-stroke engine, each piston rises and falls twice for each
>power stroke in its cylinder.  Ergo, there are 720 degrees of crankshaft
>rotation between successive power strokes on a given cylinder.
>Now envision a parallel twin.  There are two possible arrangements in
>which the two pistons can rise and fall together.  Either the two
>cylinders are perfectly synchronized and make their intake, compression
>etc. strokes simuyltaneously with each other, or the two cylinders can
>be 360 crankshaft degrees out of phase and alternate their power
>The former is referred to as a 0-degree crankshaft configuration, the
>latter as a 360-degree crank (although the crankshaft is actually
>identical for both; it's the camshafts that differ).

Hmmm.. so in theory with either engine (0 or 360) you could set it
up to run either way by altering the timing on one of the cylinder's
crankshaft (well... there is the whole sparc timing thing to deal with
too :-) ).

-- Curt

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Curtis Wilbar
Hawk Mountain Networks
rescue at

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