Engine temp

Now that IR heat guns are readily available for cheap, just wondering is there is any consensus on the 'correct' temperature as measured at the exhaust port.
I know there a lot of variables (like surface reflectivity of the valve covers), but I just did mine and got the following just below the exhaust pipe:
255 degrees left
280 degrees right
And yes, my right plug is much cleaner than the left, which is a bit oily.
Outside temp is 70 degrees and I rode for about 30 minutes before testing.

It would be interesting if you could compare your IR readings at the exhaust port with a reading taken at the spark plug via a thermocouple. Your IR may be the more accurate, for what I read of spark plug T/C's, they are notoriously inaccurate. There is no reason they should be, however, as thermocouples are industrial standards. Still, I would welcome a comparison, expecting that the temp. at the plug is lower, but how much?

Slick

PS: That 25 degree temp difference may indicate a mixture mismatch, or just oil or dirt on one side.

PPS: Are your cylinders barrels black or silver?

Do that at highway speed, and it will be something to discuss. At idle, not so much. :idea:

Slick - My barrels are black and that is where i took a reading.
Since temp difference is consistent with plug color mismatch, thinking i have either a simple carb related problem, or something more involved like a valve issue.
Will check float levels and if they match, will try changing the cool side needle jet setting.

Disagree with concours that the heat measurement at idle or just after shut down is not significant.
Would be interested to hear other folks readings in the exhaust area after a good run.

texasSlick said:

It would be interesting if you could compare your IR readings at the exhaust port with a reading taken at the spark plug via a thermocouple. Your IR may be the more accurate, for what I read of spark plug T/C's, they are notoriously inaccurate. There is no reason they should be, however, as thermocouples are industrial standards. Still, I would welcome a comparison, expecting that the temp. at the plug is lower, but how much?

Slick

PS: That 25 degree temp difference may indicate a mixture mismatch, or just oil or dirt on one side.

PPS: Are your cylinders barrels black or silver?

Click to expand...

That temp difference could also be caused by a timing mismatch. I presume you have an EI .... is the timing guaranteed to be the same on both cyls?

Most likely, it is due to mixture/throttle settings. I would be reluctant to do a radical change as you suggest ... needle position. That is a recipe to upset the entire operating range. I would first ensure the pilot jets are equal. Also check the slides are equally open at idle. Are you familiar with the test using dual 1/8 drill bits under the slides? In my experience with others who reported poor running with dual carbs, I usually found, if I got my hands and ear to their machines, they were running predominately on ONE carb.

Concours is correct in that a high speed run will elevate the head/cyl temps much more than idle. However, in my opinion, a high speed run, then quickly stopping to make a measurement of temp is reasonably indicative of the temp at speed.

Next time you shoot a temp measurement, do one at each plug as well, and report.

I am somewhat concerned about your oily plug... bad rings (why on one side?) could result in lower compression and lower cylinder temp. Low compression on one side is not unusual ... could be due to a leaky valve, score in the cyl wall, or as a Forum member (personal communication) found, due to ring gaps aligned. Maybe a compression check is in order.

Slick

Hi tomspro.
To really know what the carbys, valves, etc are doing you may need thermocouples fitted to the headers and exhaust gas temperature gauging. While cheaper, I would think a non-contact IR reading is a long way from the real action.
As texasSlick is suggesting, find the cause of the imbalance not chase symptoms and create even more imbalance.
Ta

This is what you need if you want to know the temps:
http://www.exhaustgas.com/ProductDetail ... &BasketID=

concours said:

This is what you need if you want to know the temps:
http://www.exhaustgas.com/ProductDetail ... &BasketID=

Click to expand...

i am neither a racer, nor a rocket scientist.
just a Notorn guy who want his machine to run well.
$300 vs. $15 is no contest for me.
i know IR gun is an approximation, but one that tells me something important - my cylinders are not firing equally.
an added piece of info to plug condition.

the solution is still open to speculation, and trial and error.
the way it should be for one of my engineering and mechanical background.
hate to say it... but that is "good enough" for a person just trying to get his bike to function near it's potential.

tomspro said:

the solution is still open to speculation, and trial and error.

Click to expand...

A compression gauge test of each cylinder may be more useful then,
as well as ensuring that the carbs are indeed synchronised.

If it has worn piston rings or burnt or poorly seated valves, then the cylinders may not run equally,
and a quick compression test should show this.
Incorrect or tight valve clearances could be a problem too.
hopethishelps.

Rohan said:

tomspro said:

the solution is still open to speculation, and trial and error.

Click to expand...

A compression gauge test of each cylinder may be more useful then,
as well as ensuring that the carbs are indeed synchronised.

If it has worn piston rings or burnt or poorly seated valves, then the cylinders may not run equally,
and a quick compression test should show this.
Incorrect or tight valve clearances could be a problem too.
hopethishelps.

Click to expand...

synchronization check, float level inspection, possible air leak check, and a compression test all upcoming.
the Premiers have less than 500 miles on them, but that does mean they are EXACT duplicates and one might just be out of spec with the other.
if not a carb problem, may be in for some serious engine work this winter.
just trying to eliminate the easy, less costly fixes.

Hi tomspro.
For consistent readings using your IR gauging perhaps also use a block of wood with a hole to set distances from target. If your gauge could read header temperatures, at say 25mm out from the rosette and 25mm from the pipe, I think your readings will be of more use to you for tuning. Are your readings quoted above °F or °C?
Ta.

If they were C degrees, the engine would likely be a puddle of molten metal.

Aha, I now see tomspro's hint: "...Outside temp is 70 degrees..." therefore °F.
Hi htown16.
My headers have run EGT to 780°C without the head melting.
280°C is not alloy melting temperature, it is more likely 600 to 700°+C.
Hi tomspro.
EGT gauge and thermocouples can be acquired for about AUD$30. As you are only interested in comparing RH to LH accuracy is not an issue. If you need accuracy place a thermocouple in 50/50 solder as it goes molten to assess.
Ta.

You can't actually measure exhaust gas temps with an infra-red gun, of course.
Comparing apples with oranges...

But all these temps quoted are nothing out of the ordinary.
The temps on the outside of the fins, or exhaust pipes, must be considerably less than whats inside.

Getting back to unequal cylinder running temps, have you tried changing to new spark plugs,
could be as easy as one plug not as good as it should be.

Rohan said:

You can't actually measure exhaust gas temps with an infra-red gun, of course.

Getting back to unequal cylinder running temps, have you tried changing to new spark plugs,
could be as easy as one plug not as good as it should be.

Click to expand...

multiple plug changes, some resistor, some not. some US brand, some NGK.
now with NGK platinum.
always the same temp diff and plug color diff.

similar related topic, can someone recommend a compression test gauge compatible with Norton threads?
most of the kits i see include metric thread adapters.
14mm x 1.25 ?
amazon or direct from anyone except HF link always appreciated!
$300 test tools need not apply. :mrgreen:

The spark plugs in Nortons are 14mm threads/plugs. (Why are spark plugs metric threads ??)

No need to spend hundreds to get one.
I bought a not expensive compression gauge, it only has a rubber conical bung, just press and hold it into the plughole while you kick it over.
Like this one
http://i.ebayimg.com/00/s/OTYwWDcyMA==/ ... 3/$_57.JPG

You can almost feel when you kick it over whether each cylinder has good compression,
although obviously being able to measure it is more accurate !

that's the ticket!
searching amazon now for 'rubber plug bung'.
hope i do not get into trouble! hahaha

tomspro said:

concours said:

This is what you need if you want to know the temps:
http://www.exhaustgas.com/ProductDetail ... &BasketID=

Click to expand...

i am neither a racer, nor a rocket scientist.
just a Notorn guy who want his machine to run well.
$300 vs. $15 is no contest for me.
i know IR gun is an approximation, but one that tells me something important - my cylinders are not firing equally.
an added piece of info to plug condition.

the solution is still open to speculation, and trial and error.
the way it should be for one of my engineering and mechanical background.
hate to say it... but that is "good enough" for a person just trying to get his bike to function near it's potential.

Click to expand...

I learned decades ago not to argue with an engineer

But... The temp readings at idle are so insignificant, it cant be of much value other than a steady, smooth idle/tickover. Even if you just flogged it, the thermal conductivity of the aluminum head is so great, any value is lost in seconds.

Cheap enough here? They make twins, had 'em my old free air El Tigre' http://www.bikebandit.com/aftermarket-p ... id=3104426


Twin here: http://www.aircraftspruce.com/catalog/i ... auges2.php

Re: Engine temp air cooled only

Emissivity factor range from .1 for shiney surfaces to 1.0 for a flat black surface. (users manual EXTECH model 42510A infrared thermometer) you readings could be WAY WAY off?..... not even close
IMO...paint your headers flat black or put your toy away and use thermocouples in the exhaust flow stream such as suggested by concours.
Anything much above 1325F egt will risk a seized/melted engine on the high oval at daytona...or a long run at 90+ on the highway. You may barely sustain 600-700f egt at partial throttle and may show blackened plugs eventually.
I've dynoed bikes barely running 950f egt and that is SO rich, power is way way down. It seems to be popular with guys that care more about the color of the chrome than how the bike runs.

At least thats how I see it...