Colortune

The secret to Colortune is a special, temporary spark plug with a glass viewing window. This lets you actually watch the fuel burning in your cylinder!

A handy color chart tells you whether the mixture is rich, lean or just right. As you adjust the mixture, you'll see the change instantaneously. You can rev the engine and watch the flame color during transitions, too. Use Colortune for your car, motorcycle -- even a tractor -- any engine with a standard 14mm spark plug. An essential tuning tool for carbureted or modified engines. Made in England.