I have a Ls QT 49cc Scooter, with spark plug it, it locks up the engine after a few cranks, why?

Question

This Ls QT 49cc Scooter locks up with the spark plug in and when the spark plug is removed it unlocks the engine and cranks just fine. What is causing this?

Answer 1

Did you change the spark plug? Its probably the wrong size. Always take the original spark plug to any auto parts store and the parts person can find the exact size..........

Answer 2

not the right plug