I have a 96 GSR with 70k miles. At around 3krpms to abour 3800-4000rpms, I hear a strained sound in the engine. It doesnt sound bad but it's cause of concern for me. Any clues? A friend suggested putting Valve Lifter Fluid inside the head where oil goes?

 

just a thought... but have all the regular maintenances been completed... checked belt tensions, tune-ups and the such.

does this noise happen all the time at that RPM range? or only when the AC is on?

if your AC is off when you hear the sound you may also want to do a valve job and make sure the spacing of the valves is on.

 

You don't have hydraulic lifters, so its not going to do you a bit of good. I'm having the same problem with mine right now, although the noise went from subtle to very loud.