I didn't do a compression test from several years.
What i would like to know is if an immediate rotary engine start when hot (and even cold) is a good symptom of a good compression.
My engine starts faster when hot (about 0.5/1sec) than when was cold (1/ 1.5 sec).

That means the rotor compression is good and can i avoid to do a compression test?

Thank you!

 

Typically a good hot start is a positive sign for engine compression. If you're just doing it for peace of mind, I would call it good with that.

 

+1, quick start and a smooth idle = good compression

 

idle is smooth and good, but when the engine is cold i "hear" some random misfires like some "thump" sound from exhausts.No strange sounds when the car is hot. But the rpm gauge hand is fixed even when i hear the "thump" sound. Someone told me this is normal for the wankels. Is it true?

 

I would be interested in the general consensus on that, but the cars I checked out and my own all do it to varying a degree. I would not concerned about this as long as its only an occasional gentle thump (the engine also shakes once a bit when it happens if you happen to check in the engine bay).
Although there are some factors contributing to this as my car does it a lot less than some other I checked...

 

I would not be concerned at all and quick starts when warm are typically indicative of good compression.

 

Yes the thumps will be there until it revs down. It is normal and music to my ears.