MotoGP God
Posts: 18,275
Join Date: Apr 2002
Location: Oxford
Mood: Its ONLY a Bike Club
I knew somebody would ask, didn't take long.
The answer is the piston is upside down and the inlet valve has been trying to enlarge the cut out meant for the exhaust valve.
Spooky considering my post just before leaving work at lunchtime about Bigbore kits and clearances.