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Have you calibrated this gauge according to the procedure in the factory service manual? The ohm range of the gauge seems different from the ohm range of the OEM sender.
 

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Hi Mike, I actually didn't know I needed to calibrate this gauge according to the procedure in the factory service manual, not sure how its done thanks for letting me know.
 

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The best way to check the system is place the sensor in a pot of boiling water. Water boils at 212F/100C. You should see something close.
Also, is the gauge wired separately from the factory wiring? I'm not familiar with other years but my '79 factory temp gauge is 7 volts.
There is a 7v step-down regulator attached to the underside of the speedometer. That would have to be bypassed for a 12v gauge.
 

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The ad for your gauge states "287.4-22.4Ω 40~120℃ - Type 3", suggesting that a resistance of 22.4 ohms would give a reading of 120 C. At 120 C the sending unit is at about 16.1 ohms. If this is correct then your gauge will be reading temperature but the scale will be off. That's why it might be worthwhile to calibrate the system.
 

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Thanks, Tim, I'll be doing that as soon as a get a chance. as the hook up it straight to battery and ignition and to sending unit.
 

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Bob, Not that bad here's a picture after I know where the normal range is anything over can be seen easily. IMG_20190705_173413.jpg
 

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Discussion Starter #34
Doing a coolant flush right now. Going to measure the temp with the IR Gun in a bit.

While i was letting my bike run with the water and vinegar mixture, the aftermarket temp gauge read 215 F and my IR gun measured between 94 to 100 F.

https://youtu.be/T7WnFVLp2eg

I also noticed the fan was running.

Im gonna take the temp reading again after I finish the flush but can anyone tell me what temperature starts the mechanical fan? I could see it moving.
 

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Discussion Starter #37
UPDATE:

Refilled coolant and left rad cap off and let the bike run for about 15 min. Took a reading towards the end and got these readings:

https://youtu.be/eFX4uwGrTFM


Gauge showing ~212 to 222 F:
- coolant in radiator measured ~ 169 F (my hands were shaky)
- left cylinder head measured ~ 142 F
- left rad pipe ~ 159 F


Turned off the bike and took another reading:

Gauge showing 230 F

- left cylinder head ~ 146 F
- left rad pipe ~ 153 F


CONCLUSION

I definitely need to buy a new temp gauge. Does anyone have any recommendations? Also my loom is aftermarket from Sparck Moto and doesnt need the 7v regulator. This crappy China one is wired to power, ground and the temp sender.
 

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1) Since the sender is in the thermostat housing and the temperature in other places won't be the same the best way to determine if the gauge is reading correctly is t measure the thermostat housing.
2) The laser pointer on the non contact thermometer only points to the same place as the sensor at one specific distance. Too close and the spot is above the place measured, too far and it is below.

If you didn't know either or both of those try measuring again.
 

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Discussion Starter #39 (Edited)
1) Since the sender is in the thermostat housing and the temperature in other places won't be the same the best way to determine if the gauge is reading correctly is t measure the thermostat housing.
2) The laser pointer on the non contact thermometer only points to the same place as the sensor at one specific distance. Too close and the spot is above the place measured, too far and it is below.

If you didn't know either or both of those try measuring again.
Thanks Bob I did not know either of these. I measured on the left side of the bike where I could hit the t stat housing and the t stat sensor adapter. Then I measured on the right side, where I could hit the t stat housing. The bike was running for about 10 min before I had shut it off.

Left side w/ bike on

https://youtu.be/A4eUEKaMVxw

- gauge reading ~199 F
- first measure was the t stat housing and second was the t stat sensor adapter. I couldn't get a stable reading, maybe due to the heat from me being above left side cylinder.


Right side w/ bike on

https://youtu.be/MeD62EpvlF4

- gauge reading between 210 to 220 F
- was only able to measure the t stat housing but I got a stable reading


Both sides with bike off

https://youtu.be/im8zTylj3-E

- gauge was reading 239-246 F
- I was able to get stable readings on both sides
- left side t stat housing and sensor adapter measured about 180 F
- right side t stat housing measured ~ 170ish (still close to 180)

This re test is still giving me a variance of between 40-60 F .... Anything else you suggest I try? Lol
 
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