I´m noticing some sort of knocking in the upper part of the engine after about an hour into the ride. at first i thought itwas ´cause I over heated(stuck in traffic, stop and go) but yesterday I took an alternate route and stayed on the highway and when I got off, it was there again, Im thinking its valves, but what do I know?? another thing, when I letting go of the clutch it gets this grinding sound,(again when its hot!) am i not giving enough gas, too slow on releasing the clutch??