Want to add a bigger bore to my YZ125, any advice?

[beasty6]

Hey guys,

I have got a devent amount of cash for Xmas and want to put a fresh top end in my 2001 YZ125, while I am at it, I'm thinking about getting the cylinder bored and adding a bigger high compression piston, will I have to make any modifications? Or canot I simply slap a bigger piston in there and re-jet to suite?

Any info will be great, thanks

 

[beasty6]

ah ok guys.

i did look at getting a 250 2 stroke but they just tire me out to much on the track/trails, but the 125 is a lot more tame and fun to ride, just wanted to give it a little more grunt while keeping the reliability.

it has a full DEP pipe atm, so i might get a high compression piston for the standard bore, and get a vforce3 reed valve, what else can i do to get more power out my YZ?

 

[beasty6]

would the reed valve be worth doing?