Bonneville T100 - Onboard Temp. Sensor

Mmmm well I wonder what the sensor next to the filter is????

I have the later 2019 watercooled T100.....just in the process of fitting a thermocouple engine them gauge to my bike.

I hate not have an engine temp gauge on a water cooled bike....yes I know it has the idiot temp warning bulb...bit late when that comes on.

Found a neat display unit c/w 2 thermocouples' on ebay £27GBP

Not idea yet how successful its going to be....but as long as I can see a trend I will be happy.

I can up date if interested....will work on air-cooled as well.

Not fitting the sensor under the spark plug....I am more interested in coolant temp.

Can report back if interested.....why I have it fitted.....hopfully in a few weeks.

The unit just sat on the table at home reads the room temp vey accurate.

So that encouraging.

Nick in the UK.

 

Temperature sensors are usually just thermistors whose resistance varies with temperature and hence a differing voltage drop which the ECU sees.
I doubt you'll find any specs for the OEM sensor. Typically, if diagnostic software shows a sensor fault it will be something like "open circuit" or "voltage out of range" and the sensor will just be changed for a new one.
There will probably be an intake air temperature sensor in the air box, the later water cooled twins certainly have one.
I made up a new IA sensor for my Street Scrambler which basically told the ECU that the intake air was much cooler than it actually was and richened up the mixture slightly. It certainly helped the occasional off-idle stalling stalling I had on my first one. These bikes run very lean on stock settings.

 

Maybe a useless bit of info.....but using TuneEcu on my water-cooled T100 it gives a digital temp read out I suspect the info it sends to the ECU is quite accurate as the ECU need engine temps for accurate running.

I take it your bike is the air-cooled version...to me a thermocouple set up is most likely to work.

Are you wanting a permeant display?

This is what I am going to try.

https://www.ebay.co.uk/itm/32635855...GUHlrZziQL/SR/rc0H3bjFnrbQ==|tkp:BFBMutH8q8Bl

 

Air cooled engines may be less complex to build but their cooling is less uniform and controlled than liquid cooled variants so the best place for an oil temp sensor is either the oil cooler or sump IMO.
Who knows where these sensors are made or by whom?You could always remove and calibrate it yourself to get a temp vs resistance table if you're sure it isn't faulty. I calibrated the intake air sensor on mine from -5 to + 40 deg C when I made up a replacement to give different readings.

 

If I set it up in my house it reads a very accurate room temp.....I have put the sensor in boiling water....reads about 5c down....I can live with that.....as long as its constant that will suit my needs.

But I want to be able to read trends...ie normally use on the road temps....so then if an issue develops I should see an increase away from normal.....thats all I need.

I dont have a suitable bolt or nut to put the sensor under near the cooling system so I have bonded a mild steel washer to the thermostat housing....the alloy part on the head....I will attach the sensor with a strong small powerful magnet.....and see how that shapes up.....

I can cross check the engine temps with the coolant temp that TuneEcu give me.

The unit looks well made and is waterproof....what have I to loose.

Its a similar set up to what was on my small air-cooled aircraft engine had and 1000s of other small aircraft use....there sensors normally go under a spark plug and read CHT......cylinder head temp.....

Thermocouple sensors Work great in that application.

So as I say all I need is something to indicate an away from normal temp in my cooling system.

If your looking for oil temp to give you block temp....would have thought there will be a suitable block mounting position somewhere....a sensor around the sump area or on the inlet to the oil cooler maybe????

 

My water-cooled T100 engine has cylinder head cooling fins as well as liquid cooling.....so best of both worlds.

 

If you're that concerned about engine temperatures, why not fit a reliable coolant monitoring setup like a TTO or Trailtech gauge? I've had one of these on the dirt bike for nearly 15 years and it's never let me down.
Glueing a sensor to the thermostat housing is never going to be as accurate or respond as quick as a proper coolant gauge and a 5deg C error at 100 deg is pretty rubbish anyway IMO.
https://www.ebay.co.uk/itm/28638185...e=1&gbraid=0AAAAADihhqUHn8GjK2GQNgc2uqfjh9Oze

 

That type is not great for a bonnie or me.....needs coolant holes chopping in half.....very little if any room for that.....stupid silly price...mine is a 1/3rd the price.....a battery that you cant replace.....so have to replace the lot ever 18mts or so....read quite a bit about that unit.....no idea about its accuracy.

I am not anal about the engine temp.....I only need to see a constant temp at usual road speeds.....its its going much up I need to investigate.....same if going down.....I dont need laboratory or scientific accuracy for the display....for the testing of the unit I have its seems fine temp sample rate is quite quick....5 or 10c out at 100c is neither here or there.fine for my application......I have TuneEcu to compare it to temp reading the unit gives....worth a try..

I will report back how it shapes up in practice.

 

Triumph obviously decided that the cooling capacity of the standard engine is sufficient to keep oil temperature within acceptable levels and TBH I've never come across an air cooled bike with an oil temperature gauge fitted as original equipment. I've seen a couple on tuned bikes and I fitted one to a (water cooled) car engine I rebuilt and tuned years ago.

That oil gallery plug looks very close to the exhaust?

 

If it proves to be an issue you could always try a bit of exhaust wrap to minimise heat transfer.

To get the most accurate indication of engine temperature, the sensor should be in the oil flow after flowing round the engine but before being cooled. Usually this is in the sump or return flow to the sump, prior to going through the cooler.
Fitting one in the sump obviously requires sump removal so is a lot of work compared to just replacing an oil gallery plug but only you can decide if it's worth it.
On the car engine I rebuilt it went in the sump but with the engine in bits anyway it's a no brainer.

 

Can I ask why your after the oil temp.....

 

That's a good call using the parking light circuit. Does anyone ever use parking lights anymore?