Need little bit of help. I have cleaned and replaced every part in my carb. I have set the air carb setting to where it should be. I can get the 4 wheeler started and it will run about 5 to 10 minutes then shuts off. I turn the air screw 1/4 of a turn it will start up a run for another 5 minutes. I can keep this up till the screw will not come out anymore. Does any one have any answers? Could it be the carburetor or something else.