A friend gave me this motor that had been in his father-in-law's garage for years. I have very limited experience with engines. Where do I begin? Both cylinders checked at about 90 for compression. I can not get the throttle lever to move. What does the spring in the gas cap do? Should I take apart the carburetor? How do I get the right replacement plugs? What else should I do to see if it will run? Thanks!