Temp sender

[seanr68]

Found out my temp sender is utterly sh#te, totally mis-reading the true temps. So what is the best, most accurate replacement?

Taa. 👍

[shaunthe2nd]

Could it be the temp guage that's inaccurate? Sometimes they get stripped and needle replaced in wrong position.

[shaunthe2nd]

Should have said model dependant. 4L1/4L0 type guage you can't misplace needle but on the ypvs clocks you can. What bike is it?

[seanr68]

Aug 13, 2023 11:05:39 GMT 1 shaunthe2nd said:

Should have said model dependant. 4L1/4L0 type guage you can't misplace needle but on the ypvs clocks you can. What bike is it?

Sorry, should have stated that. It's a 1981 RD350LC.

[shaunthe2nd]

There's a cheap land-rover one that fits and works well. Worth a try. Do a quick search on here and it will pop up as been discussed quite often.

[naich]

Aug 13, 2023 10:38:35 GMT 1 seanr68 said:

Found out my temp sender is utterly sh#te, totally mis-reading the true temps. So what is the best, most accurate replacement?

Taa. 👍

I've been looking in to this. The replacement ones you can buy (don't know if they are the same as the Land Rover ones) are not that great. I've come up with a really simple fix that improves the accuracy to within spec between 50 c and 100 c. It's literally just a transistor and a resistor and it works in testing although I haven't hooked it up to an actual LC gauge yet. Anyway, I'm not here for a week, but I'm planning to knock up a little module that fits between 2 connectors in the headlight shell. They should be pretty easy to make and use and I'll do them at cost to members. Happy to post the schematic if anyone is interested.

This is how the circuit works in simulation and real life looks pretty close. Blue is what it should be, red is with the sender from Norbo, and yellow is with the fix. I'll post more details later.

[seanr68]

Aug 13, 2023 16:20:29 GMT 1 naich said:

Aug 13, 2023 10:38:35 GMT 1 seanr68 said:

Found out my temp sender is utterly sh#te, totally mis-reading the true temps. So what is the best, most accurate replacement?

Taa. 👍

I've been looking in to this. The replacement ones you can buy (don't know if they are the same as the Land Rover ones) are not that great. I've come up with a really simple fix that improves the accuracy to within spec between 50 c and 100 c. It's literally just a transistor and a resistor and it works in testing although I haven't hooked it up to an actual LC gauge yet. Anyway, I'm not here for a week, but I'm planning to knock up a little module that fits between 2 connectors in the headlight shell. They should be pretty easy to make and use and I'll do them at cost to members. Happy to post the schematic if anyone is interested.

This is how the circuit works in simulation and real life looks pretty close. Blue is what it should be, red is with the sender from Norbo, and yellow is with the fix. I'll post more details later.

That looks promising, I'd definitely be interested in buy the fix/kit as and when it becomes available. 👍

[JonW]

Defo interesting idea Naich, keen to see how this works out.

[naich]

I reckon they will cost about 3 quid, tops. The postage will probably be more.

[midlifecrisisrd]

Nice fix 🤓

Steve

[crogthomas]

It's worth noting that the landrover type, as well as having the wrong resistance (although probably close enough in the range of interest), also has the wrong thread. It is a 1/8 NPT thread, but the LC uses a M10 thread in the head. It can be forced in, but that is far from ideal. Wrong resistance, wrong thread and wrong connector. But apart from that, perfect......

There is a M10 VDO sensor that should work. Still the wrong connector and not dirt cheap, but a reasonable cost I think. Details here:
rdlccrazy.proboards.com/thread/59853/m10-temperature-sender

All assuming you have checked the gauge itself is working properly?

[rigga]

Your not looking for something super accurate, after all there's not even a temp range on the guage, just a band before it goes red, all your looking for is consistency, so any change out of a normal reading, alerts you to an issue.

[cb250g5]

I believe the YPVS Y1 and Y2 heads are 1/8 NPT and the Y3 is M10. Or something like that. Landrover one has been in mine for years, working well. I know where abouts on the gauge it normally runs, so can spot if it is getting hot in traffic etc.

I doubt any 2 Yamaha ones would give the same resistance reading at the same temperature, it's a crude sender, not an accurate measuring device.

[naich]

Prototype in its box, ready for potting. I'm getting there slowly.

[naich]

Can you say "correctly reading temperature gauge with a landrover sensor"?



Here it is installed in the headlight shell.

[Tobyjugs]

In the above picture do you know the exact temperature for that needle position.
There are other explanations on this forum. I'm interested in your input.

I have done lots of temperature measurements at different areas on the engines to help me understand how these engines work. That's why I am interested in your findings.

[naich]

Sept 24, 2023 0:33:15 GMT 1 Tobyjugs said:

In the above picture do you know the exact temperature for that needle position.
There are other explanations on this forum. I'm interested in your input.

I have done lots of temperature measurements at different areas on the engines to help me understand how these engines work. That's why I am interested in your findings.

I've not measured the actual temperature, but that box brings it back in spec for most of the range:

Temperature	Spec	Measured	Fixed
50	125 R	220 R	106 R
80	48 R	72 R	44 R
100	28 R	50 R	28 R
120	17 R	30 R	19 R

"Measured" is the sensor resistance, "Fixed" is what the sensor resistance looks like to the meter, with the box connected.

[naich]

I'm in the process of knocking up a couple more of these. Does anyone fancy trying one out? No charge, but I'd like feedback on how well it works, how easy it is to install etc. PM me if you would like one.

To recap: If your temperature gauge never reads more than 1/3rd up the scale, you are probably using a sender with the wrong resistance. This box fits inside your headlamp shell between two connectors (4 way 2.8mm spade, with brown, black, blue and red/green wires), and fixes the temperature reading for a common type of sensor.

The standard connectors are male on the sender side, female on the gauge, but mine was the other way round so please check yours or ask for one without connectors so you can do it yourself.

[elsiefan]

PM sent 👍