what is a colortune?

i keep hearing it on the site here but ive never seen it in real life.
what is it?

 

the Gunson Colourtune is a tuning tool for setting your idle mixture on your carbs by being able to visually see the colour of the flame in the combustion chamber. This gives you a more efficient idle, better off-idle response, and a smoother running engine.

Here's a quick intro to it courtesy of Dwayne Verhey on the XJ mailing list:
Introduction to the Colourtune

 

the most awesome thing ever made. period.

pretty much its a clear spark plug so u can see the color of the combustion in your cylinder.

 

does anyone know where i can get one?

 

The Colortune Plug is a MAJOR Time Saving device for what Old School Tech's used to have to do "By Ear"

Being able to watch the Changing Air~Fuel Ratio change color as you Enrich or Lean-out the Pilot Mixtures saves an awful lot of time and effort tweaking the engine by ear.

BUT ... Tweaking the Engine "By Ear" will get you pretty darn close to where the Colortune Plug brings you inside of 20-seconds.

The Old Svhool -- "By Ear" Method is Tweaking and listening to the Engine.
The Mixture is Enriched listening to the Idle increase and find its plateau where additional Enriching of the Mixture has no effect.

Further Enrichment will be too much and you'll hear the Engine begin to cough, fail, backfire or stall.

The Colortune Plug allows you to look-in on the Mixture and find the optimum Air-Fuel Mixture by observing the color of the Burn during the Power Stroke.

Bunsen Burner Blue colored burn is the indicator that you have found the correct Mixture.
You can tweak without seeing the Mixture but the process is Hit and Miss.

Eventually, whether Colortuned or done "By Ear" ... the Final analysis will be how well the Bike performs coming Off-Idle and transitioning to the Main Fuel Jet Supply.

Too Lean and there is an obvious performance issue which will cause Backfire and hesitation.

Too Rich and the Bike Floods-out and stalls or Boggs-down until the Main Jet Supply self regulates and a correct Mixture results.

The Colortune Plug will allow you to watch your progress searching for the optimum Air~Fuel Mixture that will allow the Bike to Idle on its own and accelerate without a problem with enough additional Fuel in the Pilot Mixture to sustain the increased need for Fuel as the Bike comes Off-Idle transitioning to Main Jet Fuel Supply.

There is a small window of Air~Fuel Ratios that will determine whether the Bike accelerates with Speed and High Energy (A Lean Mixture) or, ... accelerates with a smooth and comfortable application of power (A Rich Mixture)

This "Window" is within a few degrees of adjustment to the Pilot Mixture Screw.
Maybe as few as two-degrees.

The Window is found by observing the Power Stroke Burn's Color and Tweaking the Pilot Mixture Screw until the Blue Color is achieved.

Further adjustment is done by Reading the Plugs for their color after the Engine has run for some time.