I have a 1995 Johnson 140 the head was totally rebuilt and I may have a total of 20 hrs on the new head. I ran double oil during a break-in phase.<br /><br />Twice running FOT at 5200 rpm the engine dropped rpm to 3500. I checked to see if I had lost a cylinder and learned that I had a fouled plug on the bottom port side. This was caused by an accumulation of metal flakes that gathered around the spark plug. (not a good sign) <br /><br />A compression check was done on all cylinders without a significant change in pressure upon comparrison. The carbs were rebuilt and the plug was replaced. <br /><br />The motor again ran well for about 2.5 hours and then it dropped rpm again from 5200 to 3500. This time it was the upper port plug that fouled in the same manner (aluminum flakes around the plug). I again performed a compression check on all cylinders and got this result <br />right top port cyl = 115 <br />all other cyl = 122. <br /><br />I also inspected all piston heads and saw that the top port side was starting to get a small hole in the center of the piston (all others were fine and flat)I did not see any other damage.<br /><br />I realize that this could be an ignition problem and that I am running lean on the port side, but what could cause this is my question ?<br /><br />I run spec oil and good (new) fuel. Plugs are gapped correctly and are champions for this engine.<br /><br />Help on this subject would be greatly appreciated.<br /><br />mrcoop
