I am trying to help my friend fix his raptor (mostly over the phone). After many failed attempts i talked him into doing a compression and leak down test. His compression was 65psi and after extensive searching on this site i believe this to be due to the decompression mechanism and normal. He then did a leakdown test and air blows out of the exhaust meaning a valve is burnt or open. My question is...does the decompression mechanism hold a valve open at all times until sufficient engine rpm is achived or does it just open one valve durring the compression stroke?