Topic: Thoughts on instrumentation

[Deltarider]

In the thread about oilcoolers it became clear that the discussion would benefit if we had more data. Our bikes standard are soberly equiped with only an oilpressure warninglight. In the posts to come I will try to shed some light on products in the market (their plusses and minusses) and which or what combination would meet our demands best.
First of all we have to distinguish our needs. There is the need to have an alarm in case something goes wrong (loss of pressure, overheating). Some of us want more and like to monitor what the actual temperature or pressure is. Then there is esthetics. Not everyone wants to bolt on just anything on a bike that is more or less original. I am one of them.
When I began riding my Four in the late seventies, some Fours would have extra gauges as shown below. The brand was Racimex, but I have seen similar that had the names VDO and Honda in their dials. I do not know whether these were genuine VDO or Honda products or counterfeit. They looked very plastic and I’ve not seen many of them. From an esthetic point of view one can say that the two gauges ‘echo’ somewhat the original layout (speedo and tacho) but, if you’d add a voltmeter that effect was spoiled. Good thing was that they were in the view of the rider. Dipstick thermometers are not and I consider them outright dangerous.
Gauges registrate, but do not warn. Best way would be an audible alarm as in aviation and shipping. On a motorcycle such an alarm is hard to achieve as we wear helmets. So we’ll have to settle with visual alarms. Now, we already have an oil warninglight for if pressure is lost, but not for oil temperature. Basically, three or four leds would be sufficient. Blue (or no led at all) would indicate that the oil has not reached its ideal temperature. A green led would indicate that the oil has reached it’s normal working temperature. Yellow would tell us we are approaching limits and red would inform us that the oil is overheating. One could do without the blue or the green led. An extinct blue led informs us that the situation is ‘green’ or an extinct green warns us that the oil has not yet reached it’s ideal working temperature. Settings for our bikes would be something like: 

          C^o     led indication        F^o
      < 80^o           blue         < 175^o 
    80^o – 115^o     green     175^o - 240^o
  115^o – 130^o     yellow     240^o - 265^o 
    > 130^o            red          > 265^o

Simple, small and cheap. For those who prefer gauges and want an alarm nonetheless, VDO offers a solution, be it that these particular instruments were ment for boaters. Like bikers, boaters do not watch gauges constantly. For this the Swiss, driven by their passion for precision, invented the makepointswitch.
The makepointswitch connected in between the sensor and the gauge will make a led light up in that gauge whenever a previously set value is exceded. Here’s the idea.

www.vettemod.com/forum/showthread.php?t=1209

With one makepointswitch you can set both a high and a low threshold. Nice is that you can program these settings by checking the needle in that gauge. You can use them in combination with temp, press and voltage gauges. Not surprisingly as they all work the same. Boaters who are often away from the dash, complete all this by connecting a warning buzzer. Or they buy this combi http://www.vdoservice.de/en/combi.shtml
With that the engine is constantly monitored. I like the idea, but not the looks. 

Here you’ll find the instructions for the makepointswitch.
http://www.maritim.no/pdf/3/Makepoint%20Switch.pdf

[Deltarider]

Let us continue our quest for the ideal SOHC-Four instrumentation. We have seen that Racimex gauges came close, but an added voltmeter would have spoiled the looks. If only they had combined that oil temp and oil press in one like the thermomanometer below… maybe.

Technically seen VDO is brilliant, but their gauges (with built in warning led) or combi-instrument (see previous post) are clearly designed for boaters and do not fit our bikes. That means we have to continue our search. Let’s start examining the sensors a bit. A temperature sensor can be put where the oildrain plug is. You can buy one new, like VDO, or find one secondhand. You can swap the drain plug with one that fits or you can even accommodate the sensor in the original drain plug by making a thread after drilling a hole (see pic below).
What a sensor does, is measure resistance and nothing else. If you make something yourself you have to know the socalled ‘kennlinie’. Practical all VDOsensors have this one for their temperaturesensors:
 
  60°C - 221,2 Ohm
  90°C -   83,0 Ohm
120°C -   36,5 Ohm

That means if you would just use a DMM you would have to learn this list by heart,

  C^o     Ohm
 65      185
 70      155
 75      131
 80      112
 85       96
 90       83
 95       71
100      62
105      54
110      47
115      41
120      36,5
125      32
130      29
135      26
140      23
145      21
150      19

Conrad had a sensor that was perfect for our goal, but I believe they’ve changed the 17mm nut for a 19 mm (see pic below) If you're interested, you can find the datasheet and 'kennlinie' here:
http://www2.produktinfo.conrad.com/datenblaetter/175000-199999/188103-da-01-de-Temperatursensor_Typ_94097.pdf

A pressure sensor works similar. VDO’s range is 10 - 184 Ohm. Another list you would have to learn . By the way, that pressure sensor is a bit more difficult to accommodate. Maybe some in this forum know the best spot. IMO a pressure gauge mounted directly on the block is – like a dipstick thermometer – out of the question for safety reasons.
(to be continued)

[jonbuoy]

If you wanted to make it dead simple you can buy small thermoswitches that close a contact when a certain temperature is reached, they come in all sorts of ranges.

[WHALEMAN]

I have VDO voltage and oil temp with a sender I tapped into the sump. Technically off to the side of the sump in the screw out plug just like the plug on the main oil galley over the point cover. Anyone want to send me one I would be glad to drill and tap. Dan

[Deltarider]

Years ago, when I was hiking through Cornwall, I got a lift in a beautifully restaurated Wolseley. The owner was very proud of his classic and showed me some of the changes he had made. After the rebuild, he wanted to be sure about the engine’s well-being at all time. On the other hand, he didn’t want gauges that would spoil the looks. He showed me how, behind a walnut panel in his dashboard, he had hidden what he called his engineguard. It was the Equus (6272A) multifunction computer meter, I’ve described before. He had set values and had attached an audible alarm as an extra. From then on, he would be alarmed, if something would reach a critical value. This way he enjoyed the blessings of modern technique and had kept his dashboard original at the same time. Whenever he was curious about temperature, pressure or voltage, he could slide open the walnut panel and have a look at the LCD screen. I thought it was a clever job and realised there are more people with classic cars and boats that would like the same. On our bikes we do not have much room. Still the idea is good. Below is a pic of a bike loaded with gauges. Personally I don't like to spoil the looks of my bike that way, while, like the Wolseley owner, I would like to know what is going on. I would like to know when…
a. the oil has reached it’s working temperature,
b. to get a warning if cilinder head or
c. oil became too hot, or
d. oilpressure... or
e. voltage dangerously low or… too high. If all of this was possible, without much distraction in my view, so much the better. What I particular liked about the Equus was, that it had a ‘scan mode’. The little LCDscreen would show alternately temperature, pressure and voltage while all was constantly monitored.
So my ideal instrumentation for my bike (and my classic boat) would be: little on the outside (LCDscreen, a few leds and some switches) and the rest of the technique hidden in a box, that can be put behind a side-panel for instance. There is a wide variety of sensors and senders available and if you search the internet, you can find their characteristics in useful datasheet. The only ‘resitance chart’ I haven’t found yet is the cilinderhead temperaturesensor http://www.machine7.com/product.php?xProd=3268&xSec=1173&jssCart=d7bfd04f376225209d467dcbce7376a5.
Maybe one of you knows. I also would like to know if there are any small oil pressure sensors.
Now, I know nothing about electronics, but I know I can put something together succesfully, providing I have a list of parts and a schematic. I've understood well there are some engineers iin this forum. Who knows, maybe they can help. 
BTW did any of you mount a knock sensor? Could be an useful extra. Can you just simply connect a knock sensor to a warning led?

[KingCustomCycles.com]

none. Seriously, look to labview data acquisition systems with a laptop or palm pc, or maybe a Graphic Engine Monitor system as used on high end aircraft.  If you are serious about instrumentation, turbine engine development test cells, and the medical industry, are way way way out there.  Like anything else, just bring a stack of Benjamins and a willing attitude....