i bought my son a 06 ltz 50 (fourstroke engine) last summer. it will start up fine with engine cold or hot, does not mater. it will make it about 10 feet then die, start and repeat. first thing i thought cloged jets. removed carberator and cleaned. reinstalled carb, same problem. i have cleaned this carberator four times. the ltz has been setting in garage since november. this is where it gets crazy. got ltz 50 out of the corner so i could try this again. charged battery and she fired right up, and guess what?? ran fine!!! my son rode it for about an hour straight. parked fourwheeler four about 2 hours then rode it for another hour. now two days later the demons have surfaced again. starts up fine then dies after about 10 to 15 ft. i did buy this ltz used so i really do not know the history of the quad. any help will be great.

 

do you still have old gas in tank or is at all new?

 

Had the same problem with my son's LT50. We drove from PA to TN for a few days of riding. Got there and his 50 wouldn't start. I thought the same as you with the jostling in the truck to TN so cleaned the carb and changed gas. Twice. No help. He rode with me the whole week. We drove home, unloaded the da#@ thing and ran like a champ with no problems afterward. Very strange. Sorry I couldn't help.
Buck

 

It seems lately that it takes a good boiling to get the problems out of a carb.
Maybe try that.