The throttle slide occasionally when at full throttle revolves round very slightly and sits on the little peg that is within the carb barrel. The reason for this in my case was that the pin was not secure and protruded further into the barrel than it should. This small peg centralizes the slide within the barrel. Consequently when we open the carb slide to see what's amiss we unknowingly dislodge the slide back to it's correct position.
Twice this happened to me on super 5s. The first time my friend thought that my riding skills were suicidal. I couldn't stop the bike in a convenient place because of heavy traffic. Ha, just passed the lot of them.