I pulled my piston and on the top it says '' 0.50''. does this this mean its bored, how do you know if its standard?
In my experience, .050 would be .050" oversize. Stock bore being 66.0mm, then a .050" oversize piston would be 67.25mm (every .010" equals .25mm)
If it truly does have ".50" stamped on the piston crown, then it's a .50mm oversize and would be a 66.50mm (pay close attention to where the decimal point is).
I wonder what brand of piston it is, since Wiseco (in my experience) always has the model number of the piston written on it. Wiseco's are easy to read too; the last four digits of the piston model number is the size (example: 573M06600 is a stock 66.0mm bore Wiseco piston for the Blaster).
After you've bored your cylinder oversize, you may be curious about your new displacement (# of cc's). Here's an easy way to figure it out...
Bore (mm) x Bore (mm) x Stroke (mm) x 0.7854 / 1000 = # of cc's
For a stock cylinder bore with stock crank, 66 x 66 x 57 x 0.7854 / 1000 = 195.008cc
If you're boring your cylinder to .060" then you'd have 67.5 x 67.5 x 57 x 0.7854 / 1000 = 203.973cc
For a Vito's +3 stroke crank, change the 57mm to 60mm, and for the Hot Rods +4 stroke crank, change the 57mm to 61mm.
I hope this is more helpful than confusing...