i took my (2) 2003 polaris Trail Boss 330 to the desert and for some reason they would not stay running without the choke on and will not idle at all. everytime i'd go down a hill and start back up they'd die SO ANNOYING! they both have 34mm CV Mikuni carbs on them.(if that helps)

is this a tuning problem or is something wrong with them. they both have the same problem and when i bought them new the guy mentioned something "notorious" about them to do with this problem and there is a "retrofit" something.....wish i listened LOL any help would be great.

 

^bump^

 

if they have been sitting for a while it's most likely gummed up carbs. very common with dirt bikes. especially the idle jet, which gets plugged with dried up gas residue. you need to take the bowl off inscrew the jet and clean it out. it is the skinny one slightly off center prodruding into the bottom of the float bowl. you can use a very fine strand of electrical wire and some choke cleaner. if the float bowl gasket is torn you will need a new one. usually they don't tear though. if you don't ride very often you should drain the carb when you get home. most carbs have a drain screw at the bottom.