Author Topic: Replace/relocate valve cover temp sensor 98 EV?  (Read 381 times)

Offline AZRider

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Replace/relocate valve cover temp sensor 98 EV?
« on: May 30, 2023, 01:36:07 AM »
Iím working on the next iteration of my retro-mod 1998 EV, and Iím 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 Iíd 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 1100ís?

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 didnít see any signs that the 1998 head had a place for the sensor just blocked off.

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

Thank you!
Trying out the motorcycle life from the other side of the counter.

Offline Wayne Orwig

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Re: Replace/relocate valve cover temp sensor 98 EV?
« Reply #1 on: May 30, 2023, 07:16:21 AM »
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.
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Offline PeteS

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Re: Replace/relocate valve cover temp sensor 98 EV?
« Reply #2 on: May 30, 2023, 09:39:42 AM »
I believe one of the ďfixesĒ 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
« Last Edit: May 30, 2023, 09:41:08 AM by PeteS »

Offline AZRider

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Re: Replace/relocate valve cover temp sensor 98 EV?
« Reply #3 on: May 30, 2023, 10:42:23 AM »
Wayne, your concern is one that I am hoping people here have insight into. Both the big and small computer versions call the sensor ďoil temperature,Ē 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 donít know if itís 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 ďresistor fake-outĒ 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 Iíve lived with it the stock way for 200,000 miles between my two 98 EVís and itís not bad.

Thank you both.
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Re: Replace/relocate valve cover temp sensor 98 EV?
« Reply #3 on: May 30, 2023, 10:42:23 AM »

Offline Vagrant

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Re: Replace/relocate valve cover temp sensor 98 EV?
« Reply #4 on: May 30, 2023, 11:27:19 AM »
My memory is short but as I recall the new ones go to metal not in oil.
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Offline Wayne Orwig

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Re: Replace/relocate valve cover temp sensor 98 EV?
« Reply #5 on: May 31, 2023, 01:18:26 PM »
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.
Scientist have discovered that people will believe anything, if you first say "Scientists have discovered...."

Offline jcctx

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Re: Replace/relocate valve cover temp sensor 98 EV?
« Reply #6 on: June 01, 2023, 10:43:34 AM »
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!!

Offline Texas Turnip

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Re: Replace/relocate valve cover temp sensor 98 EV?
« Reply #7 on: June 01, 2023, 02:27:44 PM »
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. :grin:

Tex







worked for me

Offline Wayne Orwig

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Re: Replace/relocate valve cover temp sensor 98 EV?
« Reply #8 on: June 02, 2023, 08:40:19 AM »
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.
About like this:



« Last Edit: June 02, 2023, 08:41:45 AM by Wayne Orwig »
Scientist have discovered that people will believe anything, if you first say "Scientists have discovered...."

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