Hope someone can point me in the right direction for this problem. I have a 2006 400s and it has the 3x3 / jet work done and is set up for sea level as per Eddies reccomendations. This was done many miles ago and works great. Sometimes if I accelerate hard up through the gears and shift into the next gear and hit the gas again it falls flat. It acts like all of a sudden the fuel is shut off to the main jet. It won't even rev high if I pull the clutch in. It never stalls out just won't rev high. It sputters and coughs sort of like on a rev limiter. I can pull over and stop and it idles fine. I shut it off tap the carb on the side with something hard and all is fine. It never shuts down if I rev up easy and runs fine all the way. Thanks for any suggestions on what to look for.