Hi,Im facing problerm in head valves .Right now it sounds like hell ,lot of noise coming from head .timing & crank are in right order.what should be the gap in between the valves(exhaust & inlet)by filler gadge? more over i changed the piston-ring of smaller size by 72mm insted of 75mm because of non avaliabilty of it,in india.how much CC it reduces,please help me out. thanks, bobby