Save pound’s by having the correct fuel mixture! Fuel mixture adjustment can be a hit & miss affair. Not with Colortune. This easy-to-use tool temporarily replaces one spark plug at a time providing a window into each individual combustion chamber. Adjust the mixture with the engine running until the correct bunsen blue combustion colour is achieved – job done. Works on carburettor fed & fuel-injected engines. Pays for itself in petrol savings. Its unique design maintains compression while the engine runs & ensures correct firing of the mixture. Gunson G4074 Colortune Single Plug Kit (14mm thread) fits most standard petrol engines. Colortune adaptors are also available. See the How do I adjust the carb on my vehicle ? article in the Technical Articles section