I try to tune the carb and when I turn the idle screw it works fine, turn it in and it idles it up, turn it out, idles it down, but when I turn the mixture screw in and out nothing happens. I have turned it all the way in and nothing also have taken it completely out and the engine was still running. Any advice would be greatly appreciated, thanks. I haven't checked the valves but will do that soon.

 

The tip wasn’t broke off. Did you try spraying any carb cleaner through the passage to verify it was open?