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One cylinder hotter than the other


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21 hours ago, docc said:

Well, now y'all have me interested in this temperature difference between the cylinders. I have one of those (cheap) infra-red temp readers.  But where to take the temperature? The lateral cylinder wall just below the spark plug (not the head)? Or dead on the exhaust flange?

Bad Scientists want to know . . .

venkman.jpg

 

I take a reading straight off the header pipes while it's idling. Don't really know why, or what real good it does just convenience. If I'm looking for engine temp to do the CO adjustment I take it off the area near the engine temp sensor.

Ciao   

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5 hours ago, docc said:

South'n SpineRaid TechSession?  We'll generate a Venn Diagram . . . or a Bell Curve. Or a shrug and another round of brews . . . :bier:

Solve the mysteries of the motorcycle internet, like why is one cylinder hotter than the other?  Why do the tires wear out on the left side first?  What deficiencies can we blame on ethanol? 

Just don't mention countersteering or trail braking, all fightin' words.  :luigi:

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Head temp is a direct function of exhaust gas temperature. So the nearest you can get to measuring that, is measuring the header pipe right at the head. 

I'd suggest that balancing the throttle bodies will bring it closer, and now I've got the madness to use EGT to bring my throttles into perfect balance after the static method.

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8 hours ago, Pressureangle said:

Head temp is a direct function of exhaust gas temperature. So the nearest you can get to measuring that, is measuring the header pipe right at the head. 

I'd suggest that balancing the throttle bodies will bring it closer, and now I've got the madness to use EGT to bring my throttles into perfect balance after the static method.

I think you've left out cooling. Head temp is a direct result of combustion temperature and cooling efficiency (for many various reasons, like airflow and OAT in an air cooled engine and those and other variables in a liquid cooled engine plus oil flow and oil cooling in some cases). It's a complex equation with a lot of variables.

Ciao 

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^^^ What Lucky Phil sez. BIL Harley Bob has EGTs and CHTs on all 6 cylinders of his Continental. He gets worried about them not all being the same. I told him, "too much instrumentation." :oldgit::)

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1 minute ago, Chuck said:

^^^ What Lucky Phil sez. BIL Harley Bob has EGTs and CHTs on all 6 cylinders of his Continental. He gets worried about them not all being the same. I told him, "too much instrumentation." :oldgit::)

Without a doubt. 

Ciao

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Yeah , I think a person can think too much about something . 

I can remember having a conversation one time and this guy was concerned that the engine in his car didn't stop in the same position EVERY time .

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22 minutes ago, gstallons said:

Yeah , I think a person can think too much about something . 

I can remember having a conversation one time and this guy was concerned that the engine in his car didn't stop in the same position EVERY time .

Yes, why I'm not a fan of oil pressure gauges on a Guzzi or any other bike for that matter. The complexity/ risk of failure outweighs the application and just gets you thinking about things you probably don't need to. 

Ciao

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10 minutes ago, Lucky Phil said:

Yes, why I'm not a fan of oil pressure gauges on a Guzzi or any other bike for that matter. The complexity/ risk of failure outweighs the application and just gets you thinking about things you probably don't need to. 

Ciao

I always felt that way about liquid fuel pressure gauges under the dashes of our hotrods. Always looked like one hoseclamp away from an octane soaked pantleg. :o

Not that there could have been an ignition source in the cabin back in those days . . .  :rasta:

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On 4/2/2021 at 7:14 PM, docc said:

Well, now y'all have me interested in this temperature difference between the cylinders. I have one of those (cheap) infra-red temp readers.  But where to take the temperature? The lateral cylinder wall just below the spark plug (not the head)? Or dead on the exhaust flange?

Bad Scientists want to know . . .

venkman.jpg

 

I used one of those infrared thermometers, read the valve cover, cylinder heads above the exhaust pipe, and the pipes. No crossover in front, just an "X" in the middle and then the mufflers. 

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18 minutes ago, Bob LeClair said:

I used one of those infrared thermometers, read the valve cover, cylinder heads above the exhaust pipe, and the pipes. No crossover in front, just an "X" in the middle and then the mufflers. 

I feel like I have a > Decent Tune < on MySport lately. Gonna be fun to take some temp readings all around. So many variables. Like: at start up after idling a "few" minutes? After rolling in from a ride, but not after any hard riding? Pulled in, but not idling in no air flow for any length of time ? Not even minutes? No fan over the front of the motor?

Soooo many variables to get comparable temps. :nerd: 50ºF seems like a lot of difference, but IDK.

If the exhaust temperature is, say, 500ºF, then 50ºF is 10% and, so: meh. :huh2:

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I use an infrared  thermometer and measure on the cylinder head stud next to the spark plug. I find it is more consistent than the exhaust pipe.

I also will make adjustments in tunerpro for the cylinder offset map until I get them to be 10 deg difference or less.

It is true that there are many variables that could affect the temperature. I think equalizing the temps is a good way to compensate for the many different tolerances involved.

But an accurate tune first is needed to minimise these differences. It has been a while but I think I remember getting around 260 to 280 deg on the stud.

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21 minutes ago, antmanbee said:

I use an infrared  thermometer and measure on the cylinder head stud next to the spark plug. I find it is more consistent than the exhaust pipe.

I also will make adjustments in tunerpro for the cylinder offset map until I get them to be 10 deg difference or less.

It is true that there are many variables that could affect the temperature. I think equalizing the temps is a good way to compensate for the many different tolerances involved.

But an accurate tune first is needed to minimise these differences. It has been a while but I think I remember getting around 260 to 280 deg on the stud.

I personally wouldn't be doing that.

Ciao

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One easy check is the exhaust system itself.  Especially check that either the port gaskets are a: present and, if so, b: not mullered.

I only mention as my monza was baking on one side and it turned out the gaskets had perished- one side pretty much awol which resulted in a dreadful air leak.

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