I like SeaFoam addative It does clean the combustion chamber of carbon and oil build up, same with the underside of the valves.


I'm guessing the Marvel oil cleaned his spark plugs so they fire off the fuel mixture more easily now.

+1 I also have used Marvel Mystery Oil on any used engine i get... pour a teaspoon into the spark plug holes then crank the engine to lube the cylinders. Also a decent idea to do for winter storage of a bike.

 

Marvel Mystery Oil is actually really good. My dad has been using it for years in his racing engines that he runs in his mud racers. The internal parts actually show less wear after a season of racing then before he started using it. So if it works on a 800 hp engine it should help on a 120 hp engine as well. I run it in all of my vehicles. I dont think it will give you more power, but it should help lubricate it so there is less wear which in turns helps the engine perform better longer.