for 14 mm x 1.25 spark plug thread. Allows you to see the colour of combustion in your cylinders. The kit includes a special glass topped spark plug and a reflective viewing system for difficult plug locations
the tuning plug. You don`t have to rely on expensive motortesters and false readings, with Gunson`s colortune you can actually look inside your engine, right into the combustion chamber. It doesnt`t necessarily take a college degree to adjust your fuel mixture if you can see the flamecolour, just try it out.