My son was trail riding with our Kasea 50 this weekend. He got hung up with both rear and front wheels - essentially rocks were chocking the tires pretty efficiently. He could'nt get the little bike it to overcome the blockage. Understanding that a 50cc bike has it's power limitations - when that limitation is reached -where does the slippage occur? Even with a brand new belt - will the belt always be the slippage point - or will the clutch allow the slippage? I'm trying to decide if a belt inspection/replacement is in order.
I can't make this comparison to my Polaris 500 cause power is not any issue- it will just spin the wheels in the same situation.

 

Most likely what is happening in this condition:

Your Primary clutch is engageing on the belt, and just slipping against it. If you stay in this condition long then it would cause a bad spot (Burn or wear ) on the belt. (The belt is not moving, The primary is just engaging on to it, but unable to move it)

Maybe you should take the cover off and inspect the belt. the mark should be obvious.