Tune Like a Pro

Colortune Kits $64.95: 14mm, 12mm and 10mm, Free Domestic Shipping


Colortune Instructions

Colortune Instructions

Colortune Chart

Product Info Sheet

Thread Sizes
Thread Sizes

Use Colortune when you have multiple carbs and don't want to drill ports in exhaust manifolds and you have a clear line of sight to the top of the spark plug.

In a multiple carb application you must be able to associate an exhaust stream with a carb so you can adjust each carb's fuel mixture by measuring the carb's exhaust stream. If you just want to set the fuel mixture to it's correct strength without knowing what that strength is then use colortune.

Information: The correctly proportioned mixture is - 14.7 parts of air by weight to 1 part of fuel. If there is perfect combustion, all the fuel will be burnt to produce carbon dioxide and water with no carbon monoxide or unburned fuel (hydrocarbons).

The carbon in the fuel burns with oxygen in the air to produce carbon monoxide (CO), which then burns with more oxygen to produce carbon dioxide (CO2).

Hydrogen in the fuel burns with the oxygen in the air to produce water (H2O) Nitrogen in the air passes through to the exhaust with little reaction.

When there is less air in the mixture, there is not enough oxygen to complete the burning process so some carbon monoxide is not changed to carbon dioxide and hydrocarbons (unburned fuel) may be present in the exhaust.

Carbon particles glow yellow in the combustion of a rich mixture and in severe cases you may see black carbon smoke in the exhaust.

When there is too much air in the mixture, it becomes more difficult to ignite, burns slower, and is therefore less efficient. The diluted mixture burns with a pale flame. Misfiring may occur and hydrocarbon levels in the exhaust gas will rise.

Carbon monoxide levels stay low because there is plenty of oxygen available to convert it to carbon dioxide.

Colortune - Proven Over Time

Take the guesswork out of engine tuning with Gunson's Colortune, the world famous glass topped spark plug that gives you a window into the combustion chamber so you can see the flame. Why is this important? The flame's color tells you the richness of the air fuel mixture. A yellow flame means a rich mixture and a bluish white flame a weaker mixture. A Bunsen blue flame is spot on. Colortune is so damn simple that anyone can use it. Colortune is unaffected by ambient weather conditions because it works on the law of physics that gases burn with a certain color. Remember high school chemistry lab and the Bunsen burner. So stop reading plugs and start tuning by color.

The Colortune kit includes a Colortune spark plug, viewer scope, high tension lead, and cleaning brush. Cleaning fluid no longer comes with the kit due to shipping restrictions. Use carb cleaner to remove carbon deposits from Colortune. Colortune comes in three sizes: 10mm, 12mm and 14mm. Adapters are available for the 14mm Colortune only to adapt the 14mm Colortune to 10mm, 12mm, and 18mm applications.

The 14mm Colortune fits the majority of cars and trucks; the 10mm Colortune typically fits motorcycles. Do look up your vehicle's make, model and engine size on NGK's site and note the first letter of the spark plugs' product code. Use the first letter of the product number indicates the Colortune of Colortune adapter needed.

Order the right size

Visit the NGK product guide. Next clik Quick Part Finder, then choose the vehicle type

If unsure please email me.

NGK Plugs

Use the first letter of the product code to determine the adapter. Remember colortune comes with 14mm threads.

  • A - 18mm
  • B - 14mm
  • C - 10mm
  • D - 12mm
  • J - 12mm

How to decode spark plug codes guide (NGK)

Colortune Adapters $21.95

Colortune Adapter
Colortune Adapter

12mm adapter

14mm long reach colortune adapter

14mm adapter long reach

14mm long colortune adapter

14mm adapter taper slim

10mm adapter

18mm adapter