Hello,
I have a Yamaha DT125R of the year 2000 (http://www.bikepics.com/pictures/1562742/), it´s a stock motor, but with a firebox pipe and a SPES exhaust, with carbon power reeds.
It´s has a mikuni carb VM26SS (http://img87.imageshack.us/img87/2152/cimg1063tr8.jpg), the main jet is 210, Air jet 0.7, Jet needle 5J25, pilot jet 22.5, power jet 60. I don´t understand must about carb, and i want to have more power, a friend of my tells me to change the main jet to 240, and the other jet´s remains the same? this is not going to affect the misture? I will have more performance with the 240?
i appreciate some help.... Thanks