I have a yz 426f 2001 The problems are that i can't get the bike to idle without the choke pulled out. the bike starts fine but as soon as you push the choke in the engine stalls. pull it out again and 3 kicks and it runs again on choke? Also the idle is screwed fully in so am unable to adjust any further. The bike back fires badly when rev'd but assume this is down to the fact its running on choke? Have sprayed carb cleaner around the carb and can't notice any change so assume no air leaks. I have had to fit a 45 pilot and 168 main was in just to get the bike to this point. the only mod i have done is to fit a after market fuel screw to make it easier to fine tune 2 1/2 turns out. Everything else is standard. It originally came with a 42, 168 jets but the bike wouldn't even attempt to start. Really need some help to get this bike sorted as i am going to use it on the roads as a supermoto so needs to be reliable and run smoothly. Uk is currently 20oC and i'm about 100ft above sea level.