For oil temperature readings, the probe/sensor needs to be in the oil flow path, so that engine oil is flowing over/past it, to get an accurate, average temperature reading. The best location is near the filter, where it exits the pan, on its way to lubricate and cool the engine. The pan oil is primarily the average temperature, after it has cooled off the head (can reach temperatures of 300 F), and made its way back down to the pan.
Installing a T-junction where the oil pressure sensor is located, will not work, as the oil will not flow over the sensor. You can, however, replace the pressure sensor with the temperature sensor, but you can't have both in the same location.
Oil temperatures should never get above 250 F (above this, conventional oils break down into carbon sludge), while water temperatures can reach 260 F, so the water temperature gauge will be able to handle the oil temperatures without issue. That water temperature gauge only has C(old) and H(ot) markings, so it won't be tremendously helpful, unless you put the sensor in a pot of oil (water max'es out at 212 F;
be careful heating a pan of oil...), with a thermometer, to get an idea of where 250 is on it (250 F being the thermal limit of your oil -- any hotter than that, and you have problems!). A safer option would be to run the bike to operating temperature, use a
water-based marker pen to mark the needle's position on the gauge face, then shut it down, and drain some oil from the pan, and stick a thermometer into it, to get an actual number. That way you don't have to mess with the grounding of the sensor, power, etc.
I am curious if the alternate tachometer has the same gear ratio as your bike's original gauge. Just a curious question -- I have no idea, really.
My DOHC ran, from the factory, with a heavy load (two-up, full saddlebags, full trunk, full tank bag, and both pockets of the Windjammer fairing full),
at 250 F, running 60 MPH down the highway, with an ambient temperature of 80 F. Honda designed the '79 K model to run at its thermal limit, which shortens the oil's life. If you find your oil is running at/near 250 F, either switch to a full synthetic (
Shell Rotella T6 5W-40 is excellent, rated SN for cars, CJ-4 for diesel, very affordable, too, at Wal-Mart), or consider installing an oil cooler. High oil temperatures will also shorten the life of gaskets, and seals, so even running full synthetic oils (
thermal breakdown occurs at 400 F!), your gaskets and seals will still be damaged.
Keep us informed on your progress, and what you decide to use. It's a neat idea, which I've never seen done before. Inquiring minds want to know... Cheers!
1979 CB750K (sold, 2012, but not forgotten)
1983 Kawasaki 440 LTD Belt Drive (sold, 2011)
1993 Kawasaki Voyager XII
Locked
