thanks ,i do open it up thru out the 1/2 hour many times im sorry i didnt explain that,but after the 1/2 hour or so when i open it up it fouls out. i run it the same way i use to and the plug use to have a nice brown color to it but now after the rebuild it is always black and wet and smokes alot more than before. the guy that rebuilt it said the 1 crank seal was pushed out and could have been leaning it out. could it have been that way a long time and the jetting was always rich and the pushed out seal compensated for the rich mixture ? or does boring the cylinder out 20 thousands  change the fuel/air mixture ?