help with piston size

[liljatownboy]

ok so i want to change rings on my yz 125 but dont know if it has been bored out the piston has at first a 03m or a o3m and in the middle a letter "B" than has the numbers 53.940 on the right side any help i have tried to google it but brought me to uk site

 

[yb200]

53.94 would be the size

 

[liljatownboy]

i think i foud it on wiseco website but they have three different std size pistons
01.2217.A $88.66 54.00mm STD Piston Size: 53.95mm

01.2217.B $88.66 54.00mm STD Piston Size: 53.96mm

01.2217.C $88.66 54.00mm STD Piston Size: 53.97mm

01.2217.D $88.66 54.00mm STD Piston Size: 53.97mm

 

[yb200]

from what i can find thats the standard size

 

[liljatownboy]

which one do i get? can i get the 53.97 for higher compression? its on stock bore

 

[yb200]

no get the same size you have now if it dont need a bore

 

[liljatownboy]

it dont have the same they got 53.95 .96 and .97 the bore size is 54mm i wont have to bore till i go over that

 

[liljatownboy]

why wont this work if mine is a 97 and pro x goes from 97 to 01

http://cgi.ebay.com/ebaymotors/YAMA...8266789QQptZMotorcyclesQ5fPartsQ5fAccessories

 

[blaster99]

that will work,pro x pistons are tough hard to break,id use em