Ed. You are probably correct, I am working from memory and most likely mine is 2 5/8" Ron On Fri, 12 Nov 2004 11:46:26 -0500 "ED" <edstoller at earthlink.net> writes: > Ron, > > My 4 Cylinder Hercules , Model ZXB, S/N 1159763 has a bore of 2 5/8 > ( vs > your 2 3/8 ) and a stroke of 3 inches. RPM is 1800. > > Ed