my z 400 wont idle and cuts out

[honda40031]

i have a z400 i bought it a couple of weeks ago .ween i got it started it would only run with the choke on .when i give it gas it shuts off so i changed the jet to a 142mm. now it will run but it wont idle and it acts like it is loading up and it back fires but when i get to quarter throttle to full throttle it runs great and when i let off the gas it shuts off .i have tried to use different jets and to set the idle screw and even the air fuel screw and nothing helps what do i do please help

[hang1p]

check for water in gas or clean the air filter if you can't get it to idle or come off idle that has nothing to do with your main jet so leave that were it is centrate on air screw and needle but i think your problem is somthing different then jetting

[honda40031]

thanks for the tips i changed the needle and turned the air/fuel to 2and a half turnes and i cleaned the air filter and when i cleaned the air filter i seen that the exhaust had burned a half inch hole in my air box so what i was wondered if that hole in the side of the air box would make the bike not idle and load up.i went riding today and the warmer the bike gets the worse it loads up and back fires but if im runing half or full throttle it runs like a new bike with lots of power. so i dont know what to do.do you have any other suggestions?

[hang1p]

check vaccum lines to the carb and carb boot maybe a leak somwere how about that gasket when you adj the slide is that good

[hang1p]

make sure the choke isn't stuck on even just a little visually confirm this i remember mine getting hung up