Hey, I have a 2000 Honda Shadow VT750 ACE dual-carb and I'm having trouble figuring out a high-speed issue. The bike runs and accelerates normally but tops out around 80 mph. At WOT it won't continue pulling past that.
Current setup is TJ velocity stacks, aftermarket/open exhaust with baffles,tuning kit, 145 main jets, 42 pilots, 2 needle shims per carb, and mixture screws around 2.5 turns out. I previously ran 142 mains and had basically the same 80–85 mph problem, so going to 145 didn't fix it.
Rolling slightly off WOT doesn't seem to make it pull harder either. The bike otherwise runs well and the decel popping is now gone. Before I keep changing jets, is there anything specific you've seen on these dual-carb VT750s that causes them to hit a wall around 80 mph? CV slides/diaphragms, float valves/filters, fuel pump/flow, float height, carb sync, tank vent, ignition, or something else?
Also, with velocity stacks and an open exhaust on this particular dual-carb 750, does 145/42 with two shims sound like a reasonable baseline, or would you recommend testing a different combination?
