Banging sound coming from scooter?

[DaelimRacer]

So my scooter was running well and then i noticed it was lagging and running kinda slowish. On tuesday I was out driving it around and I could hear this thumping sound coming from the scooter. It would increase and decrease in accordance with my speed.

What are some potential causes?

The belt might be getting worn out but I am not sure if that would cause it.

I checked the oil and it was super low and took almost a full litre after. It is a two stroke.

The speedometer stopped as well lately perhaps something is catching in the cable.

[jbcollier]

Put it on the centre stand and carefully rev it up and listen. Where is the noise coming from? You can use a long screwdriver to help find the noise. Hold the handle against your ear and touch the tip to various locations on the engine/tranny unit.