hardtail

hi again just took it out with filter turned at 90 degrees to the engine to allow mure air to the engine head ,a few blasts up and down the field and the perfomance dropped and 340 on my guage ,,ive got a fuel filter and motor saver on already how do you mean seal carb and back plate what exatley do you seal ... does this overheating happen when an engine is on its way out as this engine has only had about half a gallon through it im stumped