I have purchased an 18RG EFI, and decided to rebuild it, i discovered when i measured the bore, that it is 20tho OS there are no other signs of wear in the bore. it is not oval shaped or worn in any other way that i can see.my problems started when i measured the pistons. the top of the piston has 20tho clearance, but the skirt of the piston has bee flared out to only 2tho clearance. has anyone else come across this problem? any sugestions are appriciated.