Depends a lot on the prop, muffler, tach, atmospheric conditions, altitude..There is no "normal " rpm ..Most of the 100 cc engines (3W, Sachs, Quadra, BME, Mc Culloch 103 Go Kart) I test at 7000 feet with a 24-10 Glasner turn from 6600 to 7100 rpm...7200 with a 4.2 would be exceptional....