Cleaned the heat riser from the insides and painted with flat black high heat paint . Cleaning of the heat riser/inlet manifold is very important also . The function of this weird thing is to prevent icing in the carburettor and the fuel particles , and to keep the mixture proper , it drives heat from the cylinders and the exhaust muffler . The small pipe below is the one where all the "Baked Carbon" builds up and blocks it up . I'm positive about more than 60-80% beetles in pakistan having useless blocked heat risers/inlet manifolds . Cleaning is a dirty and hard task but worth it .