Buddy has a Brute Force 650 that he just bought used from a dealer. For some reason when the choke is turned off the quad idles fine but as soon as you give it gas it stalls. When the choke is on you can ride it just fine but when you stop the quad wont idle and it stalls. So you pretty much have to turn the choke off if you want it to idle but you have to put the choke on at least half way if you want to actually ride it. What could be causing this any ideas???

 

More than likely the carb jets are partially plugged up with dirt - clean your carbs and jets.

 

pilot jet in carb plugged