The Gunson Colortune plug kit is a simple and effective way to tune petrol and LPG 2-stroke and 4-stroke engines. It is easy to use and works on the principle that the combustion flame burns a particular colour depending on the fuel mixture. The Colortune is a spark plug with a glass insulator viewing window, allowing the flame to be seen. The colour of the flame inside the cylinder indicates the air-fuel ratio: yellow shows a rich mixture, bluish-white a weak mixture, and a Bunsen blue flame a balanced mixture. By adjusting the mixture screw to achieve the correct flame colour, the engine can be tuned for optimal fuel economy and performance. The kit also includes a view scope with an adjustable mirror, enabling the flame to be seen where engine access is restricted. It fits most petrol engines, with additional adaptors available for vehicles with other spark plug sizes.
