1986 Vt500c surging

[zbyrd]

I recently bought a 1986 VT500C. It is an awesome bike IMO, but it has one issue. I will describe the symptoms below:

1)Throttle response is good up to about 4-4.5k
2) At 4.5k to 5.5k the engines surges lightly. I can hold the throttle in place and it won't lose speed or bog down or anything, just surge back and forth. It feels like the engine is starved for gas
3)At 6k+, it runs smooth as glass up to the 9.5k redline.

The problem occurs in all gears, but is most noticeable at higher speeds.

Feel free to ask about anything I left out. Thanks for the help.

[storysunfolding]

Dirty carbs. Time to pull them, clean them and replace the fuel lines while you're at it in case the originals are still in there. The original lines do not work well with 10% ethanol gas.