question aboout pipe

hey guys i got a question for you. i have a 450r with a white brothers mx4 pipe. when i received the pipe, it said that i didn't ahve to rejet if i left the airbox on. well i haven't rejetted and the thing runs great. my question is, do you think it would be alright to run my quad now with the weather being around 15-25 degrees? do you think it will be too lean? thanks
travis

you may have to go up on the main ,i would think with the cooler temps,at least a fuel screw adj is in order.if you start popping on deceleration,try backing it out a lil'bit.if you go out more than 2 turns or so,the next size pilot is needed:)