I recently pulled my buddies 2001 ZX9R out of the shed after 5 years of sitting. It wasent winterized

After a lot of yelling I did an oil and oil filter, fuel filter, Gas swap,carb and choke clean... I even changed the brake fluid. After finally getting it to come back to life I noticed that it smelled like it was running rich. Not being a Gearhead I figured it was just the bad gas working its way out. I checked the fluids and to my suprise I found GAS in the oil reservoir. We have had this happen to the Grizzly 4 wheeler we had and it was a trashed petcock. No such luck this time. Petcock is aces. Any idea what I can do to fix this? Ode to a Noob.