Using a temp gauge to set air fuel mixture ?

I have recently watched a video where a technician stated that the air fuel mixture can be set by recording the temp of the exhaust pipes at the first bend. Engine at operating temperature.
States that a 80's Yamaha should read between 180 and 185 not sure if this is correct does anybody have any suggestions to either prove or disprove this theory?

Just wondering since I am unable to get my Gunson color tune not to ark all over the place inside the head.
Kinda frustrated since I spent 69.00 dollars on what I read was a real good investment.

 

Put a layer of shrink wrap over the bottom of the colortune extension to cover where it connects. Arcing will be solved.

At idle I find the colortune to have a broad range of blue flame.

I started with rich mix, drive a while, check plugs, adjust idle mix a 'dimes width', resynch carbs, drive awhile, check plugs, adjust mix, resynch carbs, clean plugs, drive awhile, etc until I snuck up on good plug color.

 

if you could read the exhaust gas temp, maybe. the pipes are double wall, maybe there's a leak? running pure gas or 10% ethanol? outside temp 40 or 85?
how long should you wait after a adjustment? is there a fan blowing on the engine?
there's just too many variables. airplanes use exhaust gas temp to set cruse mix but , well their airplanes

 

Diesel engines also use EGT sensors.

 

you could use a tachometer but you would need one for small engines that read like 4K max. set each carb to max rpm then richen each carb by some amount.
the tach on your bike can't see changes that small

 

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I did the same as this, except I started with a lean setting and new plugs. Made it easier to read the plugs. With colortune installed close pilot screw until you see some white (lean) and the open until white just disappears. Install new plugs and start the ride/adjust process. Either way will work but it might be quicker and easier starting lean.

 

I started from rich because that us where my bike was set. It would have been easier to go the other way.

 

stupid question but is it turn the air /fuel mix clockwise to lean or enrich ?

 

in (cw) is leaner

 

Thank you sir.

 

I see this reference a lot and am not really sure what this means. Are you using a dime's width to measure the rotation of the mixture screw? As in, a dime's width = 30 degrees rotation?

 

dimes width means small changes more like 15 degrees

 

I've done it that way.... seems ok. If it weren't double wall the temps would be way higher.

Where did you get your colortune plug?

 

My colortune plug was from member Chacal early this summer.

Using shrinkwrap or tape to stop arcing was the fix recommended by the Gunson, the manufacturer of colortune plug, after I contacted them about it.

I've used an infrared temp gun on my bike, but it doesn't read temps off the chrome exhaust pipe well. Temp gun manual even indicates reflective surfaces give inaccurate readings. Maybe if your exhaust pipes are rusty it would get more reliable readings?

 

paint black dots on the pipes where you want to read

 

I've never had that arcing issue

 

Gunson said they fixed it in later versions by covering the connection point, which is why they said that was also the fix. I must have gotten an early version.

 

That will work to give a much more accurate reading; the technical term when using an infrared gun is emissivity, which is a measurement of a material to emit thermal radiation in respect to a black body. Shiny objects have a low emissivity and consequently inaccurate readings are obtained when using the infrared gun.

The size of the painted surface would need to be about 1 inch square to accommodate the field of view of most guns, and the chosen paint should be a ultra flat black to more closely simulate that of a black body. That said, the issues mentioned earlier such as the double wall, the fans, and how long to wait induces variables that may be difficult to deal with. It may however be useful in identifying an especially lean condition if such a condition was suspected.

If those temps are in "F" then they are obviously way low, as anyone can attest to if they ever accidentally touched a header pipe on a fully warmed XJ.

 

I use the infrared temp gun on the top of the exhaust where it attaches to engine to make sure each cylinder is at least firing. If I get somewhat consistent readings I know they are working, but can't image it is an accurate way to measure actual mixture. Too many variables.

 

with a temp tester if you have a known good cylinder setting you can bring the others closer to that temp. at least you will be able to detect a very hot cylinder that will need adjustments of some kind . or a very cold cylinder

 

Holy cow, or should I say holy Rooster! You are a wealth of information, sir! I thought you were just an electric expert, but now I will add heat gun expert to your list. And I understood everything you said, as opposed to the electric posts!

Ps I have an ugly red welt on my ankle from when I accidentally bumped the Rebel's exhaust after a short ride. Air cooled bikes are hot!

 

wrap each pipe with bacon, the first one to drip is too lean the last to drip is too rich. adjust accordingly

 

...and then enjoy the bacon.