Howdy,<br />I have what I believe is a 1975 Merc 650 (ser#4140325)that seems to have an ignition short. When the cowl (plastic) is on, it really bogs down like it is only hitting on two of the three cylinders. If I take the cowl off, it will rev up but it still sounds as if it is missing intermittantly. The symptoms are consistant whether it is in the water or wearing the ear muffs. Jumps out of the hole and misses when the cowl is off, bogs with it on. I have recently replaced the number two piston and put new rings on all three. Compression is 120 psi on each hole. Fuel: pump, filter, and carbs have been recently replaced or rebuilt. Plugs are new. I wanted to replace cap and wires (I thought that maybe the cowl was crimping a wire), but my tech said that they rarely go bad, he tested them and verified they were o.k. According to Clymer manual, there should be no continuity between coil tower and either terminal, I am showing zero Ohms. It seems to me that the coil is next on my shopping list, but should I also be looking at the switch box?
