Beginning in 1925 a replacement for the popular model N was introduced, the NB. The NB was the first to exchange its ignitor for a Wico EK magneto and sparkplug. No igniters were ever used on the NB, some had a battery and high tension coil but the majority used the Wico. Available in 1 1/2, 2, 3, 4, 6, 8, 10 and 12 hp they effectively covered all power needs with a good selection on the smaller size engines. 1928 saw the 4 hp being re-rated to 4 1/2 hp. All engines 4 hp and up used the familiar fly ball governor, 3 hp and under used a sliding weight in the left flywheel. There were noticeable differences in the smaller engines from the previous Model N's. The NB had a mixer that bent downward much further than that of the N. The design of the governor weight and flywheels was also different. Engines 4 to 12 hp were continued as the NB until the end came in 1933. Those 1 1/2 to 3 hp fell out in favor of the NC and later ND engines.