So i purchased my first bike (03 yz125) about a month ago, and now i need a new piston head and there is a little scratch on my cylinder. Would it be smart to just purchase all new? Or is this a pretty good excuse to bore the bike out? If it is a good time to bore it out, where would i look to get this bored over, what specs, and should i run a different head? lower comp, higher comp? Thanks

Nikasil cannot be bored. You could get it re-sleeved.