how do i tell what size piston I got in my R

[pantera1975]

Pulled the top end off my 86 R and the piston looks cast and says IN on the reed side and on the side it says ART. The head gasket looked like a moose one I have and the base gasket was royal blue and white. Does that stuff sound original?

[HONDA_ATC_FREAK]

Use a digital caliper if ya got one. If you don't take it to any machine shop and ask them to measure it for you. if won't take but about five seconds and they probably wil do it for free, the ones around here will anyway.