I got a 99 YZ400F and I am having problems with it holding a normal idle the bike just received a new piston and sealings right before i got it. I have been messing with the idle but after i got it tuned in, the bike can keep the idle for a couple of minutes then it dies on me. now my question is.... Does the air/fuel mixture need to be adjusted to so i can get the bike to keep a consistent idle??? Another side question.... does the rebuilding of the motor affect the idle? (since its all new parts) I understand that the idle is adjusted ever so often but it seems like I am messing with it too much I am just very confused and just dont know what to do thanks in advance for all of the help!!!!! Patrick M.