I have been hepling a friend with his 2006 YZ450. He had to replace his carb and found one on ebay also from an 06. The original carb had a 48 pilot, 165 main, needle in stock position, and Boysen QS 3 and was running great.
Upon replacing the carb he duplicated all the above settings. Now the bike runs ok but when testing the pilot curcuit the bike would not die even with the fuel screw turned all the way in. He dropped the pilot jet to a 45 and same thing.
Could there be a problem in the carb causing this? Is it possible for 2 carbs to have several jet size discrepancy?