My bike, 93 Honda CR125, had been sitting for a few months while I was repairing the chain, bearings, and getting new tires on it. I turned off the gas and let the carb run out. I finally finished it today and it was bogging down pretty hard and it was spraying what looked like black oil out of the tail pipe. I stopped after a while but the bogging didn't. Does it need to run some more and get whatever gunk built up inside? Do I need to take the engine out and have it cleaned? Do I need a new pipe (the pipe is pretty old)?