Re: Johnson 48hp rough idle & smokes......normal?
you run it through the carb. it will clean the gum and varnish off the reeds and remove carbon from the pistons and exaust. You can use decarb or sea foam, i prefer decarb, you can get it at napa they will have to order it, or most marine dealers have it or sea foam just follow the instructions. Or you can run b-12 in your gas that also helps.