over sized piston tolerances

[riverjetboat]

Hi I have my 2001 90hp yamaha cylinder block down at the machine shop getting the #1 hole bored and they bored it 20 thousands so I ordered the .50 oversized piston and rings for it, but I need to know the tolerances for the piston to wall. Does anyone know where to find this info?

Thank you.

[99yam40]

From what I have read you normally give the piston to machine shop so they can bore block to fit.
If service manual does not have the info maybe Rodbolt17 will chime in

[rodbolt17]

the info is in your service manual.
but I can tell you, you already screwed up.

you bore the cyl to the factory dimensions. + whatever.

then you check the piston diameter and wall clearance.
its either correct or the piston is scrap.

days of boring to fit the piston are long long gone.