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Last Login: 3/5/2007 10:44:31 AM
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| How can they have a 270 degree firing sequence? If it's 270d between 1 and 2, wouldn't it be 450d between 2 and 1? What's the point. The Triumph dealer just shrugged his shoulders when I asked this question. Please give me an answer. I don't get it. Thanks
Reg Collins |
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Last Login: 3/5/2007 10:44:31 AM
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| | The original bikes had a 180 firing sequence - this means that both pistons are at the top at the same time with only one firing - the other is exhausting. A 270 sequence moves the pistons apart by that much so only one is at the top at a time creating a claimed smoother operation. |
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Last Login: 3/5/2007 10:44:31 AM
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| There is really no performance gain by using the 270 crank, it just makes it trickier to balance out the crank. Most likely, the offset was done to make the bikes motor sound better (more cadence - thwoppitty thwoppitty!)
rob@northcoastmc |
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Last Login: 3/5/2007 10:44:31 AM
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| The crankshaft is offset 270 degrees. Or 90 degrees, depending how you look at it. 360 degree motors have two pistons on the same crank pin. They both move up and down at the same time, but they fire 180 degrees apart. Meaning, when the left cylinder is firing, the right cylinder is beginning it's intake stroke.
The problem is that both pistons are moving up and down at the same time. Both pistons must change direction at the same time.
A 270 degree crank means that when one piston is changing direction (either at the top or the bottom of the stroke), the other piston is in the center of it's stroke, and is moving at high velocity. So, only one piston is changing direction at any given time, and the other piston is HELPING push it along, because it's moving at a very high rate of speed.
This allows an engine to rev much more freely. Ultimately you end up with a bang-bang-pause, bang-bang-pause, on a twin instead of bang bang bang bang.
Charles.
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