Read the thread on O2 sensors and have a question---I have access to one of those point and aim heat gun sensors---would they give an accurate reading of rich or lean?? Is it possible to have someone behind you aim it at the tailpipe on full throttle run and take a reading? And if so, what temp would you be looking for??
Anyone have a good link to learn about what the sensor actually does?? I would be interested in learning a little more.

 

PM Alltoys. He has one of those I believe.

 

OMM;

Not an expert, still asking question myself, but can answer you question I think.

The sensor doesn't sense lean or rich from the tempature, it sniffs the oxgent in the exchaust, it then sends a low voltage to the gauge.

Where the temp. comes in is this, the sensor makes it's own voltage, and needs to be heated to 600 degrees in order to create that voltage. It isn't reading heat, but need heat if you know what I mean.

On a 3-4 wire sensor, the heating element is built in and heats itself to 600 degrees and then can produce votlage on idle. The 1-2 wire sensors, need your exhaust temp to reach 600 degrees before they start sending voltage back to gauge.

To answer your question, the heat gun isn't a good tool to test jetting with. It could tell you if your running hotter than normal, but your heat light on the dash will do that.

 

Moses,
Not a smart thing to be pointing something at a tiny exhaust smoking down the road. People thought I was nuts, LOL. A heat gun will have to be to close to be used while moving. Besides you need a gun that will go into the 2000* heat range not cheap toy, a good tach with egt input is about the same price at least for me. It is possible to use temp sticks that welders use they have varied temperature melting rates that are only pennys.

XC800,
I have a new toy I would like to test on your machine when you get the time.

 

Here is a link to one of hundreds about the sensor, this sensor only has to be heated to 250 degrees. The sensor powers the gauge.

Search on google, Exhaust oxgyen sensor

sensor

 

My life insurance is paid up, lets do it. Call me this weekend, I will be at the cabin painting

 

I would get one of those O2 sensor things that everyone else is using if I had done a lot of engine mods and raised the compression. there is another reliable method.

I used to use thermocouples in the exhaust port. Basically I would drill a 1/8" hole and insert a the thermocouple probe into the exhaust flow as near to the exhaust port as possible.

Exhaust gas should only be about 1250F. If it is under 1200F it often indicates rich misture. If it is higher it means too lean (like 1350 or higher).

That is a very reliable way to test engine running condition, but many people do not want a 1/8" hole in the pipe. You almost can't burn a hole in a piston if the exhaust comes out 1250F.

BTW, you can't get a good reading from a gun pointed at the exhaust pipe itself. The pipe thickness, the color inside the pipe, color outside the pipe, shape of the pipe, chroming, performance coatings, and airflow around the pipe all affect the heat transfer from the pipe to it's surroundings. Radiation is probably the dominant heat transfer mode with a hot exhaust pipe, and with so many variables, I doubt you could count on a reading of the surface of the pipe to tell you anything useful.

 

I got an idea, send me something to test. hehe. I wish. Someday I will get to Alberta, its going to be great!

 

My EGT can change as much as 100*F, depending on ambient temp. It is not a good tool used alone; I used it in addition to a WBO2. EGT is more of a combustion efficiency indication, rather than AFR. For example, my normal range of WOT EGT is 1500*F...I can add so much fuel, that my EGT will increase to 1550 or higher. That is the effect of unburned fuel burning in the hot header pipe. HTH

Steve

 

Hope everyone still looks at this thread because I am confused on something---Heard a couple of comments especially after installing the offset key that their electric cooling fans are hardly coming on after certain mods. I do realize that I have an oil cooling fan compared to the water cooling fans on the 650/700---but if you are running at peak AFR shouldnt the fan come on about the same??? My engine is running the besy it ever has---I checked the plug and it looks tan/to white after full throttle run which I find acceptable, but my fan seems to come on an awful lot

any comment??