carb seems to be giving out at high speeds

[Rich P]

Sounds like fuel filter but could be other things as well. Change the fuel filter(s) since it is a relatively simple thing to do and probably needs to be done anyway. Find the drian plug on the bottom of each carb and open them up (do not drop the plugs) to let whatever is in the float bowl out and then use the primer bulb to shoot a little clean gas through there. Replace plugs and when there is no more gas fumes take her for a spin. If problem persists, you might need to disassemble and clean the carbs, might have a coil that is malfunctioning when hot, or might have a fuel vent restriction. Good luck.
-Rich