Piston ring size

[yozzer74]

I'm wanting to buy some new piston rings but how do you tell what size they are can't see any marks on pistons to see if there' standard or over size .??

[hairygit]

If they are genuine pistons (hm stamped in the little depressd area where the gudgeon pin goes in) and no markings on the crown, they are standard size.

[yozzer74]

Thanks I will check that out tomorrow

[Bryanj]

Check on the top surface of the rings, no markings mean standard or you see25; 50; 75; 1.00 or something very similar

[AshimotoK0]

I have also seen ART marked on OEM pistond and no HM logo. On twins models though.

[hairygit]

I have also seen ART marked on OEM pistond and no HM logo. On twins models though.

Yes, I found  ART on my CB175 pistons, but the fours I have worked on tended to be HM, although the general rule seems to be even if pattern pistons are fitted, if they are standard size they have no markings on the crown, whereas oversize ones have the oversize stamped on the crown, and as Bryan said, the rings are often marked too, although some people fit oversize rings and file the ends to fit standard pistons, so the crown is the most reliable guide,