Normally I'd run a piston for between 50-60 miles and pull the top end off. Take any high spots off the piston skirts, relive the rings lands and chamfer the ring end.

I'll run piston rings for around 250 miles on a 250 and pistons for about 600 miles. On the 500V the ring is 1mm rather than a 250's 0.8mm so they are staying in a little longer.

Once this first service is done nothing else should really be needed apart from the normal stripping and inspecting for the life of the pistons/rings.
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If I have to take the carbs off once more...