i've got an 85 350x bored over .020 with a 400ex head pipe and cobra pipe, 400ex carb with carb boot and head ported to match, the exaust gasket matched to head pipe. i am running a 190 main jet with the airbox lid on, the plug is lightish brown. when i am in sixth gear wide open the motor loses power like it is hitting the revlimiter, but i can pull the clutch in without litting off of the throttle and it will rev higher and then hit the rev limiter.
any suggestions as to why this is happening.
ps stock gearing with 22in pro wedges