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11gram difference in pistons??

Practical Engine Building

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I began to apply the piston balancing process to my v twin yamaha rebuild but immediately hit an curious issue. piston 1 weights: 450g, piston 2: 461g. they are factory pistons from a 70,000km engine. is it normal, is it safe, to remove 11gram from a piston?? thanks

I once had to remove 18 grams from the piston. It is doable as long as you know where it can be removed from. There is a webinar here with Andre demonstrateing the exact areas for piston weight removal.

That's a heck of a lot for a Japanese manufacturer, they're usually very close.

Are they the same bore size, might have had one cylinder bored out for a cheap 'fix' by a previous owner?

You may be able to mix and match the gudgeon (AKA piston, wrist) pin and connecting rods to better balance the reciprocating mass, well worth checking their mass as well?

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