I could be wrong here but if your leaking coolant from the decomp plug you would have more problems than a coolant leak. I would clean the area well and spray foot powder around the front of the engine. You will be able to see the leak better that way. Also I would be looking around where the coolant pipe enters the motor just above the exhaust pipe and more center to left of the front because the only seal there is an oring and if the pipe and oring arent just right you will have a leak for sure. And from experience dont ever miss handle that pipe because just one small bolt holds it in place.