Author Topic: DYNAMIC BALANCING  (Read 2033 times)

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Offline polly

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« on: 05 Aug 2014 at 12:58 »
does any one know what percentage is used to balance the crankshaft on a 600 S/V aero please?? david

Offline Doug

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« Reply #1 on: 05 Aug 2014 at 21:43 »

Zero in the sense that you are probably thinking. Each connecting rod and piston are counterbalanced by the other connecting rod and piston. The counterweights that you see on the crankshaft are really there to help balance out the rocking couple due to the slight offset of the cylinder. So saying it is 48% balanced - or something to that effect - is not comparable to values you see for singles or parallel twins because it is not counterbalancing the same thing.


Offline eddie

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« Reply #2 on: 06 Aug 2014 at 07:37 »
          As Doug says, the balance factor is less important on flat twin crankshafts than on singles or parallel twins. Provided it hasn't been modified, the crankshaft itself should still be balanced as it was when it left the factory. What may upset the balance is the possible replacement of either the conrods or the pistons - they should be fitted as matched pairs to get a perfectly smooth running engine. Checking the weight of the pistons is easy, but the conrods have to be supported in a horizontal position so that the weights of both the small ends and bigends can be checked and matched.