Digital oil and coolant temperature display.
In the name of CX research and development,footerin`,fiddlin`,messin` about,and inspired by the work in Cxism i have knocked up a cheap method of reading the temperature of the engines vital fluids using a modified domestic digital kitchen thermometer.
On a more practical note i also wanted to get an idea of the temperature inside the engine to check that the resin i used on my rewound stator was not being compromised - the upper temperature spec was stated as 120 C.I also had doubts over the accuracy of the STD CX coolant temp gauge.
This is what i started off with - a cheapo kitchen temp gauge bought from fleabay for a few quid.With a little bit of micro-surgery and weilding a soldering iron i transformed it into another useful*/useless* gadget to adorn the inside of my CX`s fairing.
First thing i did was to take it apart.
It`s one of those things that isn`t supposed to be taken apart,but that has never stopped me taking stuff apart before....
I removed the end cap and prised the two halves apart - its glued together,so easy does it.
Next,i unsoldered the board from the probe.The `buisiness end` has a tiny electronic component (probably a NTC resistor?) with a coating of heat-sink compound and a couple of thin-gauge wire leads inside a polythene sleeve - thats the white thing in the pic.I`ll call it the thermocouple.
I removed that then persuaded the stainless tube the thermocouple fits in out of the plastic case.Thats glued in too.
I then replaced the stainless tube with some suitable 2-core wire and soldered it up to the board,then re-assembled the case,glued it back together and fitted the battery and cap.
This wire then went to a miniature changeover switch.
I have two thermocouples;one in the sump plug,the other in the radiator top-tank.The switch will change from one to the other.
For the oil temperature sensor i fitted the thermocouple into the oil pan via the drain plug - the CX650`s have a small `sump` which is ideal for the location of this.
This is the second bike i have done this modification - the first time i used the original stainless steel probe and fitted it into the drilled sump plug with a 4mm compression gland.
This has worked OK,but the wall thickness of the stainless tube is very thin,and deforms under the pressure of tightening the gland.It did not make a 100% oil-tight fit and although It does not leak to any degree,the fitting is wet with oil and i may get one drip off it after the bike has stopped.You can see the first effort in the top,right pic.
So,the second time i made this gadget i sourced some 4mm brass tube from a modellers shop and soldered it into the drilled sump plug.This has been totally oil tight.Obviously the end of the brass tube has to be sealed as its inside the engine and i did this with more solder to form a stop-end.
I connected some more of the 2-core wire to the thermocouple leads then slid it into the brass tube.
I crimped the end of the brass tube over the 2-core to act as a strain-relief and then put some braided wire over that to give it some abrasion resistance.
Connect to changeover switch.
For the coolant temperature i fitted the thermocouple into the radiator top tank - this won`t tell you what the coolant`s doing while the thermostat is closed/while warming up,but when the `stat opens the temperature rise is obvious and gives a reading of the coolant temp just after it exits the thermostat housing/top hose.
I bought another kitchen thermometer(only needed the thermocouple from this one) and used the brass tube method again.
I hammered a punch (!!) through the top tank in my chosen position.I didn`t drill the hole because i wanted the copper tank to deform and form a `well` before the hole was formed that would hold more solder and hopefully provide a more secure join for the tube.The tank is made from copper which is easily workable/soldered,but i had to be careful not to impart too much heat in case the tank/matrix core soldered join was compromised.Again,the inside end of the brass tube was blanked off..
Another length of 2-core was joined on to the thermocouple which i removed from the thermometer and crimped in the brass tube,braid applied and i hooked it up to the other side of the switch inside the fairing.Jobsagoodun.
Observations.
Coolant and oil temperature are not directly related.
As long as the bike is moving and has airflow through the rad the coolant is fairly stable but oil temp will vary with the load on the engine.
For example,stop in traffic and the coolant temp will quickly rise,but because the engine is mostly idling the oil temp will be low.
Now get out of that traffic jam and hit the motorway at 75mph the coolant temp will fall as the airflow cools the radiator but the oil temp will rise as the engine woks harder (the 650`s also have additional oil jets aimed under the pistons which will help suck heat away from the combustion chamber).
Oil temp:
Low engine speeds/idling about 80 - 85C
High speed/working the engine harder highest temp i have seen is 107C.
Coolant temp:
Thermostat appears to be fully open at about 82-84 C - when the thermostat opens and coolant is flowing freely this is what is shown on the gauge.
When the needle settles on the part of the temp gauge in the clocks where the thin/thick line meet the digi gauge shows 84 C,half way is about 90 C.
Normal running temp `in the cruise` is about 84 - 86 C,depending on ambient temperature.
Electric fan cuts in at about 103 C - this is the temp in the top-tank,the lower tank with the sender will be slightly lower. (the fan lowers coolant temp surprisingly quickly).The 650`s tend to run hotter than the 500`s - i might have to fit another Digi-doo-dah to the Ratfighter to compare!
Oil temperature is less affected by ambient/seasonal temperature than the coolant.
Strangely,the 650`s have a smaller capacity radiator than the 500`s.
The larger engined bikes have a two-row coolant-tube rad where as the 500`s have three.This may expalin why the coolant temp on 650`s tend to rise sharply whenever the bike has stopped (in traffic for example) or when travelling slowly in hot weather (filtering through traffic).
My 500 `Euratsport` is also fitted with a 650 radiator and displays these signs of high coolant temp when stationary and idling.
It`s on my `to-do list` to fit a 500 rad to see if things improve...
Cockpit gadgets;
Temperature gadget is also usefull for checking fluid temps when stored in my garage.During a spell of cold weather recently i could check the state of the oil/coolant;the oil temp was down to 0 - 2C,so that 20W-50 oil i was using in the summer would be a no-go in the winter.......
Air pressure gauge - forks.
Whilst decommissioning/dismantling an industrial machine at work i found a couple of these digital air pressure gauges and thought hmmm,they`re handy little gismo`s - too good to throw away,where can i put one of those? The CX-Periment,thats where..
I initially thought that because of where they were being used on the machine they were only for measuring very low pressure levels (say up to 15psi or so) but after checking them out on the web i found they were good up to 10bar,so the obvious place for them would be either end of the bike on the forks or Prolink.
Of course it`s not really necessary to have a permanent readout of the air preload in the suspension system but it is handy to have an accurate idea of how much air you`re putting in when using a bicycle pump on the forks, the pressure is so low (0-6psi on the 650`s) that an ordinary tyre gauge is not accurate enough,and just using one to check the pressure lets most of the air out when you release the gauge anyway!Besides,this digi gauge was free,and it`s another gadget to amuse myself with (or add unnecessary complications,depending on your point of view..),and it`ll get other folk wondering just what this intriguing technical-looking readout measures! Well,we all like gadgets,don`t we? I`ll even be able to see the pressure rise when the forks compress when braking.Wow......
Having the forks linked does make adding air easier though,and both sides will be exactly the same.
To install it i took the stanchion air caps off and drilled/tapped them to accept the screw-in air fitting.The air hose from both forks met at a T-junction and from there the hose was routed up the handlebars to the gauge,which needed the 12V supply hooking up to a switched +ve on ignition switch-on.I put some heat-shrink tube around the body of the gauge to give a degree of weatherproofing.Knock up a small bracket and fix to brake resevoir bolt.Thats it.
Next,i`m on the lookout for a vacuum gauge to measure inlet manifold pressure......
Contact Ofapars;
