if you suspect the oil injection system of malfunctioning, disable it and pre-mix a tank of gasoline and oil.. results will reveal if the oil injection is the problem or not.
a bike that's been sitting for years normally develops fuel system troubles, mostly related to gasoline's tendancy to oxidize and decompose over time This leaves behind varnish in delicate areas.
Symptoms usually include plug fouling from too much fuel.. one common cause is a leaking float needle valve.
Another common situation is no start due to the opposite .. no fuel delivery due to a clog somewhere in the fuel pathway.
So the residue from deteriorated fuel can cause both too much fuel and not enough fuel delivery.