HarleyTechTalk

Harbor Freight temp gun test. Note, water boils at 212f.

https://www.youtube.com/watch?v=khBRd7UWsck

Quote from: 86fxwg on August 18, 2015, 07:40:55 PM

Quote from: Bikerscum on August 18, 2015, 05:17:52 PM
I shot mine with the handheld when I got home from work today.... 236 front 241 rear right next to the plugs. Powervision reads about 15 degrees higher. Ambient temp 102. I think the highest I've ever seen the PV read is 270 something.

'15 wethead, V&H Power Duals & Twin Slash Rounds, 57H.

Must be a Walmart temp gun,any Max 

86

One of the times I ran my egc on the dyno, I was seeing about 10-20 degrees higher sampled on the Tmax as what the operator was seeing on a IR sensor as we warmed the motor up.. It was cool that day and we were having trouble get the head temp above 200F where the tmax would start correcting PW offsets..  The operator was pointing the gun at the black section right next to the where the head sensor was..  Sounds like they might have been walmart guns but location is everything.. Was that your point? 

Quote from: PoorUB on August 18, 2015, 07:32:46 AM
IMO, I don't believe you can get any valuable head temp info from a infrared temp gun. First, what part of the head to you shoot, and second, what temp are you looking for? I have seen engine temps on my 2010 over 380F from the stock sensor that is mounted on the back of the front head. The exhaust side had to be well over 400F, probably closer to 450F. The engine has survived these temps with no ill effects at least as far as I can tell.

I checked the rear head after heat soak behind the spark plug (on right side above the exhaust port) and I got a reading of 470* ......front head was in the 350* range. Is it normal to have that much of a difference between the two heads?  Holy smokes that picture Coyote posted is crazy as hell.

IMO All the "tuners" should have a answer for this !!!!!!!!!!!!!!!!
INCLUDING last posted #27

On my Ultra I have seen 80* difference from front to rear with the lowers on, with the lowers removed they are within 10* of each other. temps always taken within 30 seconds or so after engine is shut down , try checking on the spark plug side between the plug and head bolt and the IR gun needs to be almost touching the head "the further away the larger the area that your sampling"

Quote from: Bikerscum on August 18, 2015, 08:11:26 PM
Harbor Freight temp gun test. Note, water boils at 212f.

https://www.youtube.com/watch?v=khBRd7UWsck

Pretty good, maybe 2% off, just like my high dollar Fluke that I probably paid 5 times as much!

Quote from: gabbyduffy on August 19, 2015, 02:26:53 AM

Quote from: PoorUB on August 18, 2015, 07:32:46 AM
IMO, I don't believe you can get any valuable head temp info from a infrared temp gun. First, what part of the head to you shoot, and second, what temp are you looking for? I have seen engine temps on my 2010 over 380F from the stock sensor that is mounted on the back of the front head. The exhaust side had to be well over 400F, probably closer to 450F. The engine has survived these temps with no ill effects at least as far as I can tell.

I checked the rear head after heat soak behind the spark plug (on right side above the exhaust port) and I got a reading of 470* ......front head was in the 350* range. Is it normal to have that much of a difference between the two heads?  Holy smokes that picture Coyote posted is crazy as hell.

470 is seems too high.. I've seen 350 and not much more.. Maybe the laser pointer is not in line with the sensing device and you are picking up on the exhaust pipe.. Could be that the sensor is not focused correctly.. The laser has absolutely nothing to do with the device measurement.. It's only an siting tool.. Try holding the thing upside-down and see if the measurement changes.

Quote from: Max Headflow on August 19, 2015, 05:32:37 AM

Quote from: gabbyduffy on August 19, 2015, 02:26:53 AM

Quote from: PoorUB on August 18, 2015, 07:32:46 AM
IMO, I don't believe you can get any valuable head temp info from a infrared temp gun. First, what part of the head to you shoot, and second, what temp are you looking for? I have seen engine temps on my 2010 over 380F from the stock sensor that is mounted on the back of the front head. The exhaust side had to be well over 400F, probably closer to 450F. The engine has survived these temps with no ill effects at least as far as I can tell.

I checked the rear head after heat soak behind the spark plug (on right side above the exhaust port) and I got a reading of 470* ......front head was in the 350* range. Is it normal to have that much of a difference between the two heads?  Holy smokes that picture Coyote posted is crazy as hell.

470 is seems too high.. I've seen 350 and not much more.. Maybe the laser pointer is not in line with the sensing device and you are picking up on the exhaust pipe.. Could be that the sensor is not focused correctly.. The laser has absolutely nothing to do with the device measurement.. It's only an siting tool.. Try holding the thing upside-down and see if the measurement changes.

I here you Max, I'm pretty sure the rear head is hotter then it should be. I just got back from dropping the bike off at the tuners, I'd rather be safe then sorry.

The laser is a lot narrower than the ir.

You could be picking up the exhaust temp instead of the head temp.
If you haven't done it already, I'd try different aiming angles to leave
the exhaust effect out of it.

Quote from: TJAH on August 19, 2015, 02:11:56 PM
The laser is a lot narrower than the ir.

You could be picking up the exhaust temp instead of the head temp.
If you haven't done it already, I'd try different aiming angles to leave
the exhaust effect out of it.

The beam pattern is often printed on the side of the device..

  I check my cheapo H/F laser with the boiling water test yesterday to see how accurate it was. It read 211* when the water started to boil.
  So I went out and rode my bike for an hour and then checked the head temps. I haven't checked them since I first started this engine a few years ago and did the heat cycles.
  My front head was 242*...which was shot right above each p/rod tube and at different angles front to rear...and the rear head was 244* shooting it the same way. Down at the V of the cases between the cylinders it read 190*.
  If I shot the heads closer towards the exhaust (1/2"- 3/4" away from the end of the head)...the head temps went up into the 260*- 265* range.
On the other side...aiming it to just to one side of the spark plug...it read 240*.
This was done on a well heat soaked engine with the bike running and no cooling fans turned on.

Ray

Spend a little more on the IR gun with two laser dots that are calibrated to give you the right distance to what your are measuring.  quite a difference in temp reading at different distances.  with two laser dot, you move the gun in or out till both dots are in the same spot of what you are measuring.... 

The temperature of the tool itself is a factor in its reading.  Any two readings relatively instantaneously made will be pretty good against each other for comparison purposes, but if the unit has been in a cold garage and brought into a warm house, for example, you'll want the temperature of the tool to stabilize with the surrounding air before getting picky (as much as you can) with results.

What you're pointing it at makes a difference, too.  Check out https://en.wikipedia.org/wiki/Emissivity#Emissivities_of_common_surfaces.  You can see what happens when you compare a spot on the cylinder fins and one on the chrome rocker covers (room temperature is most informative).  The emissivity for which a unit is "calibrated" is sometimes indicated on a label or a manual if supplied.  I think it'd be safe to consider a reading on a bare pine 2x4 (wherever that comes in on that list above) to be pretty accurate.

I use my HF IR gun a lot, I love to drive myself crazy I guess. IMO it is a good tool for comparisons. For instance, I always check temps for the hottest reading on the heads at the exh. side of the spark plug. I know that my head temps are 30°-40° cooler on my S&S 124" compared to my previous 117". When my heads are running 330°F the threaded hole for the front head temp sensor reads around 270°-280°F. For me the IR gun is another good tool to help understand what the engine is doing or how it is responding.

I just had my engine tuned on Fri. & on Sat. went for a good long ride in the northern Az. mtns., on the way back into Phx. we were riding in 108°+ temps for the last 1-1.5 hrs. doing a consistent 80 mph. When I got home both cyls were within 10° of each other & at the temps noted above. Based on previous observations I know that is pretty darn good considering the riding conditions & duration.

Quote from: Coyote on August 18, 2015, 07:36:39 AM
I need to borrow one of those temp guns. 

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How to stress relieve a pipe.
Ron