Tank: fill with Acetone (1 gallon) and soak it, swish it around, and drain. This will help with dissolving the evaporated fuel.
Engine: remove spark plugs. Spray some penetrating oil directly into the cylinders and let soak. If the motor will allow you to rotate it with the kick starter, do so several times with the plugs out. If all is decent there, drain oil, remove filter, and replace these. Rplace plugs with new set. Attempt to start the bike (this after carb rebuild and tank service).
Carbs: remove bowls, soak them in a solution to dissolve all varnish, remove jets, needles and emulsion tubes. Clean, clean, clean them. Reset float heights. Basically, you are rebuilding and restoring them to factory settings. Tons of threads on here about carb rebuild and the approximate settings and sources for parts.
Download a copy of the manual, and perform the 3,000 mile service also. This will entail servicing the brakes, the master cylinder, adjusting and lubricating the clutch, brake and throttle cables. Change and replace the fork oil. Check the swing arm bushing for play, the steering head bearings for wear, and of course, the wheel bearings.
All this will likely take about 2 weeks if your diligent and reference the manual as you go. When you get stuck, post up a question and some pictures, and many knowledgable members will come running to your aide.
