Yamaha fzr 1000 exup 1990, bike's been standing for about 2 years, it start's and run's great but the clutch will not disengage, feel good at lever.

This happens after they sit a while, get her started, get her rolling, put her in second gear, hold the clutch in, get her up to 20 miles an hour, hold a little throttle on and slam on the rear brake, this usually will free up the stuck friction plates. If not try it a couple of times, it has always worked for me, also if that does not work for you you have to take the side cover off of the engine (clutch side) and using a flat headed screwdriver, and a zip tie to hold the clutch lever back to the handle bar, place the screwdriver in between the clutch plates and gently pry them apart from each other, on your bike I believe you have 7 friction plates and 6 steel plates. ( if you have to remove the cover go get a gasket first).