over reving? please help

[dieselissues04]

I bought a pw50 3 days ago for my little and the guy that sold it to me said it hasn't ran for 3 years. I drained oil and fuel and got fresh stuff also cleaned out the carb and kicked it over. it runs fine in start but as soon as I put in to run seems like it want to take off on me? I took it apart again and everything seems normal I twisted the throttle and I didn't see any movement of the butterfly or needle. now on the top side of the carb theres a brass plunger looking this on the throttle side is the whole this suppose to move or just the needle? thank u

[steveh]

the whole thing has to move. It may not be seated down all the way.

[boaty]

Any chance you put the slide in backwards? It will still go in but wont drop down all the way, thus holding the slide up causing it to rev up on startup.