88/89 Mariner 100 4 cyl. Serial # B209468 & up.<br />Motor will run OK but not as well as it's mate, (dual 100's), and now after 15min., bad misfire. Two top plugs look good, 2 lower, black soot.<br />Changed out stator & trigger,(red stator upgrade), and 4 new coils, same deal. Can I now be sure that it is the switch box? Also, what is an acceptable compression test for this motor? Thanks. CC
