Friend has brought his 92 gpx250 to me to fix (I do IT by day, just hobby mechanic learning as I go by night) he told me he accidently put too long spark plugs in and when he tried to start the piston hit the plug. I've popped the head off and can see a small dent on the piston from impact, what should I expect to replace. I'm presuming the piston, but it's gudeon pin seem solid should stuff like that go too? Should both sides be done (one piston dented one was scratched. I've rebuilt air cooled 750s and gpz600r's but nothing with serious physical damage yet so sorry in advance if I sound noobish.