I'm having same issue with my HJR engine. Kevin did a 4mil with pump gas doms and I put it together over the winter. I have t5 exhaust,28mm pwk Jetting about same as yours. I will need to look to be sure, Went by what Kevin told me to start at. Vforce 4 reeds, Hotrods 4 mill crank. Will start on 1-2 kicks and idles fine. If you rev it seems fine. Take off, once you get to mid range falls flat on its face. Sputters runs like shit, pull in the clutch and rev it up it will start to pull. Will run better on top, but does not feel like a 4 mill. My dads stock banshee with t5 exhaust will smoke me. I only ride at Pismo dunes, but you cant even ride it if our not on the top end all the time. I tried switching,stators cdi etc with my dads banshee, nothing changes. My frame was painted and I sanded the grounds down to the bear metal. Should I try running another ground for my engine? Was wondering if that could be the problem?