only thing above the head gasket would be the valve caps right? check the orings on them, they might leak some. but that wouldnt cause it to run bad unless the valves were wacked out of adjustment. check the timing in it, i used to have problems with my 200x's cdi box, make my machine run like dog___. just a suggestion.
1985 KXT 250 Tecate - kx cylinder, kx ignition, bassani headpipe, answer silencer, v-force reeds, 38mm airstyker carb, +2 franks swinger, raptor rear shock.
1996 YSF240 Blaster - maxxed out!!!
Life's journey is not to arrive at the grave safely in a well preserved body, but rather to skid in sideways, totally worn out, shouting "HOLY SH-T, what a ride!"