Hey all! I'm new to the XR650 board as I am posting a question regarding a friend's bike...hope someone can help or offer some insight! Anyway, my friend just got done uncorking his 2001 XR650 and after completion of the mods it spits and sputters past half throttle. The mods included, drilling out and removing the baffle in the silencer, replacing the intake manifold and removing the airbox restriciton. He of course rejetted, changing the pilot jet, raising the needle (lowering clip position) and went up to a 175 main. Sorry I don't have the exact specs on clip osition and pilot, but I believe he used specs posted on this forum. Anyway, when he took it out to see how this newfound power would behave, but all he found was a really bad sputter above half throttle. He lives in MI and the temp was ~20 degrees F when he ran it. I suggested that it may be entirely too lean with all the extra air getting to the motor, since the air temp was only 20 and the jetting specs he got I am thinking were for 65 or so and sea level. He says it feels like it is getting too much fuel but I have not had a chance to take a look at it to confirm one way or the other. Has anyone else run into a similar symptom when making thses mods? My first suggestion was to go up several sizes on the main and see if it gets better, worse or stays the same...however, my friend then informed me he mistakenly removed the needle jet and moved the hex nut adjuster (which I believe affects the height of the needle jet in the carb?!). He feels he put it back where it was, but I am thinking without measuring and having it set at the correct height +/- 1mm will have an affect on performance?! So that's the story - ANY input woud be greatly appreciated!! Ride Red!!