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are there any advantages to buying balanced pistons.?

i have been looking for pistons for my sled on ebay.There is one guy that is selling balanced pistons for my sled. But they are 50.00 more than his regular pistons. What is the advantage to balanced pistons.?
 

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are there any advantages to buying balanced pistons.?

i have been looking for pistons for my sled on ebay.There is one guy that is selling balanced pistons for my sled. But they are 50.00 more than his regular pistons. What is the advantage to balanced pistons.?[/b]
I'm not sure about sleds....but in cars it would not make any difference unless the rods are balanced too! It an assembly so if the rods are not balanced too it would not make any difference when you put them on the rods.
 

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are there any advantages to buying balanced pistons.?

i have been looking for pistons for my sled on ebay.There is one guy that is selling balanced pistons for my sled. But they are 50.00 more than his regular pistons. What is the advantage to balanced pistons.?[/b]
Sorry to be the one to tell you, but I think your being led down the garden path. Most pistons are close within a few grams of each other. Over sized pistons weigh about the same. Piston crowns on over sizes are usually cut down a couple of thousandths (1/10Th of one ratio point) to accommodate even power delivery. Two cylinder 2 cycle engines are inherently unbalanced due to the fact that the crank is phased 180 degrees and power cycle occurs every 1/2 rotation of the crankshaft (180 degrees). The counter weights on the crank are balanced to match the weight of the piston, ring, wrist pin & clips at a theoretical 5000 rpm (representing mid point of torque curve) on most 2 cylinder two stroke cycle engines made by Rotax. Ask the seller how he / the manufacturer balances the pistons for some proof. I have had on some occasions to remove a little material on the underside of pistons to make their weight "dead equal" for ultra high rpm racing motors where it's not uncommon to spin the tach well past 13,000 rpm that being the exception not the rule. You can always weigh your reciprocating assembly with an inexpensive postal scale. I have weighed many brands of pistons including OEM and found them of similar weight. The only wild card here is molecular weight or density which describes the difference between cast (poured into static vacuum mold) or forged (compression extruded into shape) or Hypereutectic which are cast then roll hardened on a three axis press under 30 tons of force (similar to case hardening).
 

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Discussion Starter #4
Sorry to be the one to tell you, but I think your being led down the garden path. Most pistons are close within a few grams of each other. Over sized pistons weigh about the same. Piston crowns on over sizes are usually cut down a couple of thousandths (1/Th of one ratio point) to accommodate even power delivery. Two cylinder 2 cycle engines are inherently unbalanced due to the fact that the crank is phased 180 degrees and power cycle occurs every 1/2 rotation of the crankshaft (180 degrees). The counter weights on the crank are balanced to match the weight of the piston, ring, wrist pin & clips at a theoretical 5000 rpm (representing mid point of torque curve) on most 2 cylinder two stroke cycle engines made by Rotax. Ask the seller how he / the manufacturer balances the pistons for some proof. I have had on some occasions to remove a little material on the underside of pistons to make their weight "dead equal" for ultra high rpm racing motors where it's not uncommon to spin the tach well past 13,000 rpm that being the exception not the rule. You can always weigh your reciprocating assembly with an inexpensive postal scale. I have weighed many brands of pistons including OEM and found them of similar weight. The only wild card here is molecular weight or density which describes the difference between cast (poured into static vacuum mold) or forged (compression extruded into shape) or Hypereutectic which are cast then roll hardened on a three axis press under 30 tons of force (similar to case hardening).[/b]


Thanks for the info I will keep my 50.00 and buy the rugular pistons.!!!!!!!
 
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