[PatNY]

Try this:

1. Check for air leak by the Intake
Spray some carb. cleaner and see if there's any response change
(may need a new Intake Manifold)

2. Clean Carburetor (let it soak over night)

3. Drain & Clean Fuel Tank
(Might need a new Petcock)

4. Get a New Fuel Filter and clean/buy a Fine Mesh Filter

5. Check the floats in the carb.
(Might be stuck)

6. To be in the safe side, buy some new main jets, pilot jets
and a new spark plugs to tune it up.

I don't know what mods were done to it, but if the stock air
box was removed and replaced with something like a UNI then
go with bigger jets.