if it's got an rg piston
I would put a new one back in and leave it verymuch alone 
the bike runs well very well why bother changing anything that you dont have to change ??????
you will only muck it up 
so as F5Dave say rebore it and put the next oversized piston in
checking that its the same as what came out
Dave D spent a lot of money on that bike and had someone do the work to it
so I wouldn't try and make it any better (Yet )
my 2 cents worth ( have seen a lot of good bikes stuffed up because someone thought they new better than the origanal builder )
ps I think all 50cc suzuki pistons are the same ???? at least the part number for the Lt50 quad and rgvr50 and any other kids stuff I have found where the same
"Instructions are just the manufacturers opinion on how to install it" Tim Taylor of "Tool Time"
Saying what we think gives us a wider conversational range than saying what we know. - Cullen Hightower
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