After another 3 or 4 gal you'll be at about 7400rpm. These Sachs type engines really run best between 7200-7400 rpm on the ground. I'm not knocking 7100, that's good too, but they definitely need to be propped above 7000.
ORIGINAL: bhole74
My BME 50 is happy spinning a 3W 22x8 at 7100, but I only have one gallon through it so far.