Replace/relocate valve cover temp sensor 98 EV?

[AZRider]

I’m working on the next iteration of my retro-mod 1998 EV, and I’m having a clearance issue with the temp sensor in the left valve cover.
Since that location has a bad reputation for false readings and that sensor has a bad reputation for weeping oil (my bike has both of those problems), I figured I’d ask if anyone has ever tried either relocating the sensor to a different location, or relocating AND using the newer sensor found on the 1999 and newer 1100’s?

I checked, both sensors are supposed to report the same resistance value for any given temperature.

I had the thought that the new style sensor could be mounted in the sump or plumbed into the oil feed or return from the head, since I didn’t see any signs that the 1998 head had a place for the sensor just blocked off.

Before I try to reinvent the wheel, I’m curious if this has been done before.

Thank you!

[Wayne Orwig]

I think there is a reason they measure head temperature, not oil temp.

I would try to get a thermistor with the proper specs, easy to do. And JB Weld that into an aluminum plate (washer) that is under a valve cover screw head. If you do that where there is not a lot of air cooling it off, that should work.

[PeteS]

I believe one of the “fixes” back in the day was to add some resistance in series with the thermistor so the CPU read a temperature higher than the thermistor was reading. I know I did this to my 98 but no idea what value I used. Somewhere out there, there is a chart of temp vs resistance for that thermistor.
Pyro Dan, you still out there?

Pete

[AZRider]

Wayne, your concern is one that I am hoping people here have insight into. Both the big and small computer versions call the sensor “oil temperature,” both use a thermistor with identical heat/resistance curves over an identical temperature range, and both are located in the oil flow on the head. So I don’t know if it’s important to read the oil temperature AT THE HEAD or just anywhere that the oil is hot enough to tell the computer that the engine is cold, up to temperature, or too hot.

Pete, I remembered the “resistor fake-out” trick and I even found and re-read the old thread to see if there was anything relevant in it. Unfortunately, the problem I really need to solve is relocating the sensor for clearance reasons. Getting more accurate readings would be a bonus but I’ve lived with it the stock way for 200,000 miles between my two 98 EV’s and it’s not bad.

Thank you both.

[Vagrant]

My memory is short but as I recall the new ones go to metal not in oil.

[Wayne Orwig]

My memory is short but as I recall the new ones go to metal not in oil.

Yes the new one is a metal thermistor, bumped against a metal threaded tip (even if the housing is plastic it is still a metal tip). Screwed into the aluminum head.

[jcctx]

Seems I read about 20 years ago you could just sub a resistor (value??) to ground for the "run" (warm??) value on a switch and use it like a "choke". Off for start and on for run!!
Perhaps Wayne could comment!!

[Texas Turnip]

My '98 would get 20 mpg when the temp was below zero until I put on an on/off switch. Ride it for 20 minutes and flip the switch fooling the sensor. BTW I did a Saddle Sore Iron Butt 1000 in Jan. Worked for me and I'm not a member of KERA.

Tex







worked for me

[Wayne Orwig]

Seems I read about 20 years ago you could just sub a resistor (value??) to ground for the "run" (warm??) value on a switch and use it like a "choke". Off for start and on for run!!

Yes, the temp sensor is in a poor location. The valve cover will never ever get up to temperature in the winter. So, the ECU was always on 'choke' so to speak, pouring in too much fuel, in the winter.
Some people paralleled a switched in resistor, to fool the thermistor into think the motor was hot.

I have to wonder if mounting the thermistor under a valve cover bolt wouldn't help a lot.
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