Ok listen carfully, this is a frustrating problem but I strongly recomend that you not run your engine till the problem is fixed. Your engine is overheating that is the grinding sound from the piston bieng dry and scuffing the cylinder wall. your overheated engine is overheating the condensor which is failing at the high temp, that's why it needs to cool down for two reasons to cool the condensor and to allow for the piston to shrink a bit as it cools and allow for an easyer glide. Mostlikley your engine is not getting the petrol that it needs probably from a carb issue. You are doing damage to your engine everytime you run it, if you want to keep your bike find out why it is overheating and fix the problem before it is too late.