most has been covered, you have old tyres probably time to change the rear. been sat a while on it may have distorted casing, low mileage for year.
wheel bearings, swing arm linkage bearings, head bearings. don't forget sprocket carrier bearing.
buckled rim or discs. centrifugal forces unbalance; borrow a dial indicator and base.
sticking pads, wheels in line
correct quantity and weight of fork oil, could be fork bushing.. you wont know any of this unless stripped
if all ok, heavier bar weights might help
