You'll need to buy a tach with most any four-stroke, and they'll all need to be broken in below a certain RPM level.
I don't use a tach. My OS four stroke has a simple two fuel tank run in procedure. No RPM limits and no tach required. I am not suggesting that you do this but after running one tank it was so sweet I flew it (with a rich needle setting!)
It is now on about 10 flights and purrs!