86 tri-z tuning

[Stephon_xr500]

So I'm still battling with my top end tuning, it was sitting for a month but before that I had cleaned the carb. It starts with out any issue once the pump is primed. It has no issues when in neutral and I hit the throttle, does not bog... but as soon as I am riding and a give it about 1/3 twist it flattens out instead of hitting the powerband. There are no air leaks, yz250 carb with a 420 main jet. I've got an aftermarket pipe but I'm not sure what it is.

The fuel delivery system works fine.... gas Poors out if I take the main line off the carb while running.

[Stephon_xr500]

I adjusted the slide needle it was 2nd from lowest position now it's one notch above the highest position. The motor will get in to the powerband now but still feels flat. I'll be picking up some main jets tomorrow I'm thinking around 500