Don,t stress 2 much mate most motors will hiss as u wind them over by hand! Best thing to do is to beg,borrow a compression tester, with all spark plugs out, crank motor over using starter motor at least 5 times with foot flat on the accelerater, compression tester should show I guess anywhere from 140 to 200 depending on the condition of the motor ok anything less than this{unless u got a fairly decent cam in it}is pretty ornery and I,d prolly rebuild it ok