Mikuni Parts help?

[FMS88]

Another odd thing is that the choke doesn't open all the way. I have no clue how to adjust that. Maybe at highway speed it's not getting enough Air instead of not getting enough fuel?

If the choke isn't opening it will sputter from lack of air. It isn't really adjustable but with a fully warm engine, the choke butterfly should be completely open (vertical). If it stays mostly closed, check that the red wire to the choke has 12v while the engine is running. If not, check the wire on both sides of the eight-pin connector, and then the same red wire at the choke relay and the black/white wire to the choke relay. The relay is in the "device box" attached to the driver's side wheel well.

Check the accelerator pump operation. Remove the air cleaner top with the engine not running. While looking down into the primary throat, quickly open the throttle linkage. You should see a small stream of fuel squirt down into the primary venturi. If nothing or it only drips some, the accelerator pump circuit is obstructed and that can cause the drivability issues you described.

Lastly, with the exception of the idle speed screw, resist the temptation to adjust any of the other screws. Most are set at the factory (or by a rebuilder). "Adjusting" them can make matters worse at this point.