190cc 4t Zip will not idle

Starts and rides but will not idle, when the throttle is held in one place, the revs go up and down and still will not idle, any ideas on what it could be!!

 

could be an air leak

 

Tried for an air leak and all seems to be good, i have no idea what else it could be

 

Idle screw

 

Blocked idle jet

 

checked all things mentioned and all seem fine, i have sent my carb off to be cleaned with a air compression kit, it may be blocked deep inside where i cannot reach. (I HOPE!)

 

Which type carb are you using?

 

I am running the standard carb as far as I am aware, the main jet is 83 if that helps.