i am posting this for a friend.
he has a 2006 CRF450X
he has an aftermarket airfilter, opened air box and he has a PC silencer on it.
his jetting specs are
170 main
red JD needle on the 3rd clip
he just installed an R&D power pump and R&D flexible fuel screw. he set the pump to where the leak would be a 60.
when we start the bike it starts up fine with the choke on but no matter how warm it is when you put the choke off it dies pretty much immediately. also, with the choke on or off giving it gas causes it to sputter and backfire.
we tried changing the pilot from a 45 to a 48 and he says that just made it worse.