Engine compression, bad rings, etc.
How do I suspect if my engine is having a bad compression, leaking rings, head gasket, etc?
I can't say I'm noticing any lack of power - the engine works the same way it did 6 months (3k miles) ago. It does not consume much oil - in 5 months (some 2.5k miles) oil came down to a bit over a half. Sparks are in a very good shape - not greasy, not black, not burned, just normal wear. I just noticed today, after driving in the city for some 30 minutes, that my oil pressure gauge showed something a bit under 3. It is usualy at the upper end, like around 4 - 4.5, but I can't really say I ever checked it when idling - just riding. As I pt it in idle today, on a warm engine, it went down to under 3. If I pushed the gas pedal, it went back up. Letting go the gas and it went back down. In the morning, when it's cold, I crank the engine up and it goes from 0 to some 4. Then I begin riding and (again) I can't say I checked it, so that's why I got worried when I saw it going low today, idling.
Are those readings normal? Does the oil pressure always go that way? Or is something wrong with compression?
Also, when I'm in the city, and all that stop-and-go stuff when it's crowdy, it sometime happens that, if I start moving (1st gear) but don't put it in 2nd cos the cue stops, but rather step on the clutch and let go of the gas and brake, it goes wery low on RPM, almost dies. It comes back to normal almost that moment, but for a second it seems to be stalling. Then another couple of times that effect doesn't show up. And other times it comes up again. Also happens (not always) if I give it a bit of gas when idling. Then the rpm goes up some, and when I release the gas pedal, it (sometimes) goes stalling. But it gets itself out & adds a couple of rpms (all by itself) and continues to work normally.
Is that normal?