I have an 86 250 racer, and i am thinking about putting a big bore kit on it. i have heard rumors that the 85 and 86 lower ends are not as strong as the newer models and i will have to rebuild the lower end when i do the top end. if anyone has done this to their machine or knows someone that has any info would be appriciated. also does anyone know if i will have get a new carb or just rejet the old one.