Motorcycle Repair: engine, oil tank, oil light

Question
My engine suddenly started missing and knocking. I noticed oil  in my air filter when I stopped. I didnt ride far after the noise began. What would you suggest.

Answer
Hope you are talking about a Harley. Next time: year, model, mileage, and more accurate description of where the noise seems to be coming from.  Oil in the air filter is normal from the top end breathers.  Did you check your plugs to see if they are wet with oil?  Plenty oil in the oil tank?  When you start the bike can you see oil returning to the tank when you look in the dipstick hole?  Is the oil light on?