My 94 GSR idle kind or low, around 500, and idles really rough. It also burns just a tad bit of oil, and runs very rich (black smoke, build up on plugs), and conmpression is around 160 all the way across. Does this sound like valves or stem seals? I've also heard that it could be that the timing is off, does that sound right.

 

If it was the valve or stem seals you would most likely see blue smoke on start up. I would do a leakdown test to see where you are loosing it.

As for running rich and idle that could be a million things. Have you done a tune up recently; plugs, cap rotors, fuel/air filter, plug wires, change oil and oil filter, etc. I would start there with the simple and cheap things, then continue to work on it.

 

Yeah, the tune up is done, with all things mentioned.