I have an aprilia rs50 which runs fine, until I just let it tick over. When ticking over it appears too much oil gets on the spark plug and stops it sparking in the right place.

Its an NGK spark plug, and i'm getting the problem of the spark being down inside the plug, not on the tip. Isn't it a stupid design to allow it to spark inside, or is there a reason for it?

Any thoughts?

Cheers

The plug is knackered/dirty.
Welcome to two -strokes
Check the oil mix if it's a pre mix, else the regulating system if it's a seperate tank.
Don't sit with it ticking over unnessesarilyy, give it some thrash

2 stroke oil pump not adjusted correctly??

and use top quality oil

Cheers guys, will check those things over. Thanks