Just pulled my YB pistons out. Never pulled a YB apart before, done lots of bikes etc.
I have some scoring vertically in the bore on the outside edges of the bore. This sides closest to the outside edges of block which I guess is where the pressure from crank movement comes into play.

How much is normal on YBs - none, some ... Is this something you fix with a light hone ?
What do I do to minimize this from occurring ?

There is no lip at the top of the bore. What measurements should I take to see what acceptable wear is on the pistons, if I need new ones.. same applies for rings and bearings. What are tolerances.

Any help appreciated.
Gavan