New Carb backfire problem

[Labbo]

Hi, Newbie here. I have a 2006 Precedent with the FE350 engine. I just replaced the carburetor and now have a backfire problem. The engine also seem to starve for fuel, intermittently, when I run at 32 to 3400 rpm The rpm limiter is disconnected. The butterfly seems to close normally. Pilot screw is out 1 1/2 turns. I have tried going down to one turn and up to 2 turns.
Also, after changing the carb I find that the speed has increased dramatically.
Sorry to be long winded.

[Larry1950]

Backfiring or coughing is a lean condition. The pilot screw controls idle mixture. If you are running that fast probably what is happening is the float bowl is being drained faster than the fuel pump can keep up. Check for kinked fuel line, plugged fuel filter, crude in the needle and seat, poor fuel pump operation. Also check your valve lash. Those engines were never meant to turn a lot of rpm's and is very easy to float the valves. Quite possibly damaging the engine.

[Labbo]

Thanks. I know that I should not rev near 4000rpm but what is a safe
rpm to cruise at?

[Larry1950]

That is why there is a rev limiter, to prevent engine damage. The limiters are usually set 3500 to 4000 rpm or so. The thing is most cart engines are seriously detuned. Very mild cam timing, small ports, weak valve springs, small valves, restricted exhaust, small carb, etc. And yet get big money for a under built motor.