[03black400ex]

More questions...i just bought this 400ex and it runs good when on the gas but wont idle. talk to the guy that had it before me and he said it idled in the summer and that he thinks its bad gas...hard to believe. i have yet to take the carb off and clean it and put new gas in but he also said he never rejetted it. has full fmf exhaust with power bomb header and k and n filter. and should i be rejetting for summer vs winter or no? im use to having my 03 Arctic Cat F7 with efi so im not use to the whole jetting the carb scene.

 

[90vfradam]

Cleaning the tank out and carb isnt too bad of a job..

Did you try to adjust the idle on the left side of the carb there is an adjusting screw that sticks out.. Turning this can increase or decrease your idle speed

 

[Here 2 help]

Bad gas is a possibility if it's over 3 months old. Can you make it idle by holding the throttle just off the throttle stop? Then just adjust the idle speed with the adjuster screw. For winter riding, the main jet could be bumped up about 2 sizes over stock. With the exhaust and K&N filter it should be bumped about 2 sizes already. And, with those changes, it may idle better if the air/fuel screw is reset about 1 turn out. If all is tried and all is good, look into getting the carb cleaned. Drain the carb each time it's going to be parked for more than a couple of weeks to prevent gumming up.