A A A A Author Topic: CX Temperature sender to Moto-Gadget  (Read 121 times)


CX Temperature sender to Moto-Gadget
« Started on: 15-Aug-20, 14:37 »
Hi Guys

I'd like to share with you a problem I have had with the engine temperature on my CX500 and CX650
At first I built a CX500 with Moto-Gadget control and Moto-Gadget speedo that has a digital temp readout built into the gauge
Taking that bike out for a ride on a reasonably cool day the temp would be up around 105C-120C this did worry me
I had cleaned out all cooling galleries in the overhaul. The thermostat was checked and it was opening at 82C
I had fitted a Kawasaki ZX6R Fan and sender with manual override. The direction of the fan was checked for flow (Drawing air through the radiator and out towards the back of the bike) I would keep the fan on manual override and still temp was high
A CX650 motor came along and I overhauled the motor and fitted it into the bike with the original CX650 radiator and fan and fan switch on the bottom of the tank
Ran the bike and still had the same problem, high temp !
I then bought an after market temp gauge and sender and temporary fitted it to the bike and temperatures were now correct running at 85C to 90C radiator fan sensor OEM cutting in at 102C  I had changed that to a Kawasaki one that starts the fan at 90C
So all that boiled down to the wrong temperature sender from the thermostat. I have now ordered a Moto-Gadget sender so finger crossed the readings will now be correct   


Re: CX Temperature sender to Moto-Gadget
« Reply #1 on: 15-Aug-20, 15:34 »
The CX temp gauges run on seven volts (not 12) and I suspect the sender unit is calibrated for this voltage. With an aftermarket gauge and original sensor I am not really surprised your temp reading was off.

In hindsight maybe a check with an Infra Red temp gauge would have helped to prove the actual temp as OK.



Re: CX Temperature sender to Moto-Gadget
« Reply #2 on: 15-Aug-20, 21:56 »
Hi Seagrass

Yeah the CX uses a 7V transformer. I did change the original OEM water temp sensor for a "Tridon" TCS133 and got the same readings on the Moto-Gadget speedo
Hopefully the a Moto-gadget sensor will read correctly
I now confident the bike is running in spec on the temp and have disconnected the Temporary temp gauge and sensor and just waiting on a moto-gadget sensor  to arrive 


Re: CX Temperature sender to Moto-Gadget
« Reply #3 on: 16-Aug-20, 07:17 »
Keep in mind that the purpose of a pressurised system is to run the engine at more than 100C for better fuel economy.  According to the Haynes manual page 100 the system is designed to have a max pressure of 14.9psi and that would make the boiling point with cap on 125c.  Of course the running temp is somewhere below this but above 100.

"Young" Les F


Re: CX Temperature sender to Moto-Gadget
« Reply #4 on: 16-Aug-20, 09:24 »
Hi Onetrack

Point taken
Looking at most auto temp gauges they are calibrated between 40 C and 120 C
The Moto-Gadget speedo is the same after 120 it doesn't  register and my temp on a warm day was going off scale
When I fitted the aftermarket temp gauge and sender. I took my CX650 for a ride around town on a cool winters day in Adelaide and when I pulled up at home the temperature at the thermostat was 88 C the thermostat is partially open I'm thinking this is one of the hottest areas of the motor.
Also because I have had this false temp problem due to the wrong sender I was running the radiator fan on manual override  and the OEM sender on the radiator, rated at 102 C was changed to a 90 C and the fan was cutting in at 90 at the traffic lights
Now I'm thinking that the temps are OK I fit the new Moto-Gadget sender to hopefully give me the correct readout on the speedo and change the radiator fan sender back to the OEM one of 102C
After all Honda know how to design motors LOL


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