I have a 9.9 1976 Mariner by Yamaha serial # 682 C 250663.It has been setting up for a while .It starts very easy runs very strong but it has a 'miss' or skip at wot.I have changed the plugs, cleaned & rebuilt carb.Am pretty sure it is the top cylinder because I can pull plug wire from bottom it stalls and shuts down,when I replace that one and pull the top wire it misses but still runs.I have switched the coils but to no effect.Compression is 95 on both cylinders.Can anyone help me?By the way what are the two lines comming out of the carb going to the cylinders for? Are these vacuum lines,does anyone know. My next experiment is to replace those.Thanks.
