1989 30HP Evinrude missing at midrange

Hi Folks, <br /><br />I've just rebuilt my power head, the plugs were clean and found that the cylinder head and block were warped. Got the motor back together and now I have this problem. Runs great at idle and from midrange to WOT, but the engine misses in the midrange. Another clue, the top plug is wet while the bottom is dry but black. I switched the ignition, meaning I swapped the plugwires and wires to the primaries ... same result, so it looks like I can discount the ignition. Thinking that it may have something to do with the high bow before she planes off. In that vein I bent the float tang in the carb to try and help lean things out, no change. The thermostat was just replaced and the temperature seems to be fine (by the touch of the hand)<br /><br />Any advice would be greatly appreciated. <br /><br />~John

Re: 1989 30HP Evinrude missing at midrange

Your float should be level with the carb when turned upside down. Sounds like you might have a weak cylinder. Did you do a compression test after your rebuild? Could be a bad vacuum hose also.

Re: 1989 30HP Evinrude missing at midrange

Sorry, I forgot to add that when you put your hand on the cylinder head you should only be able to hold it on there two to four seconds before you are forced to remove it and stick it in the cooler.

Re: 1989 30HP Evinrude missing at midrange

Thanks for your response. It's hard to beleive that a cylinder is weak when the motor runs so good at high speeds, but you may have something there. When the motor was apart I didn't check cylinder and piston measurement because it looked so good, i.e. the factory hone marks were still visible. I did however make the typical newbie mistake and didn't have my rings lined up when I crunched in the ring squeaser .... CRACK. So ther are a new set of rings inside that may not be seating properly. A compression check is definately in order. I will write back in a few days with the result. Thanks again.<br /><br />~John