???? What am I missing on this set up
OTO19231...2000 EFI With 4 hole intake and a set of Boysen 250 XB Reeds, cut Heads at 63cc they were 250 EFI heads he cut... Motor runs real strong with stock 225 boxes... got another set of boxes reflash by Eric Simon. 300ING/250xb fuel... motor launches out of hole great but hits a wall around 5200 and falls flat and starts to surge... so I eased back to landing. Put stock boxes back on and runs super... Right up to 5900 and pulls real strong... figured it must be in the boxes... So I order a brand new set of 250XB boxes.. guess what does exactly the same thing... runs up strong to 4800 and starts the surging again... hits a wall at 5200rpms... What is missing with this application... Need some imput please... runs perfect with stock boxes