Struggling with some issues on a 836 honda. Stock carbs with 4.5 lbs of fuel pressure. Idles great nice and strong. Runs up to about half throttle then lays on its face. Fuel pressure is constant. Dropping the fuel pressure to 3 makes it worse. Car also idles high after coming off racetrack for a few moments. engine ran great on a smaller track 2 weeks ago with 3 lbs of fuel pressure. The 1/4 mile track is where we are having this problem at least this week.

To me this is a dead give away of not enough fuel. However my experience has all been with aftermarket flat slide carbs or fuel injection all on newer engines so I'm lost with this old motor on old stock carbs. Am i correct with wanting to go with a bigger main jet? or do i need to just sink it in a lake?