I bought this sled about a month ago a 93 EXT 580 Mountian Cat with and 94 ZR440 engine. The guy I bought it from said it just needed the main jets replaced well he was wrong seems more problems then what he led on to be so far I have proceeded to replace the bad gas rebuild the carbs, replace the jets and plugs, checked the fuel pump apperes to be doing its job, and I have been tweeking the hell out of the dang air screw but I still cant get it to run right. Seems to start fine with help from the choke will even rev fine around 3k rpm but after it warms up and it drops to idle w/ or w/o choke it will slowly kill itself sometimes I can save it if I feather the throttle, after it dies I have to attempt to start it with the choke open then turn choke off and it will start but still will not remain running for more then 5 min. Sounds to me like its not getting enough gas to maintain itself however im new to snowmachines and even moreso into 2-strokes. Would anyone be able to help with my problem or give me the specs on what the Jets sizes should be?