I will measure the inside diameter of the radiator hose right now, and report back shortly. ;)

The hose fitting on the top of the right radiator has an outside diameter of 3/4-inch. Therefore, the inside diameter of the hoses appears to 3/4-inch. ;)

Brilliant spud, thanks :tup:

we have a fit :)

this must be a carry over conversation from advrider. hope the bringing up the thermobob ends up being of some benefit to you guys.

is that 3/4 at the narrow part or 3/4 at the flare?

I've been having to fill my reservoir twice this week. Any ideas?? I commute highway speeds each day 60 to 100 miles each weekday.

Temp readings on the NC250
 

In the name of scientific research I took the Zong out for a ride, with stops to measure the temperature of various parts of the engine and cooling system. Overall this was an hour of riding with a couple 3-4 minute breaks. I used an IR meter that has been pretty accurate in the past.

https://photos.smugmug.com/Motorcycl...O/Scan%201.jpg

Bottom line, the engine never got hot enough to burn off fuel or moisture in the oil. Note that the measurements on the left engine cover really do not show the oil temp whereas the measurements on the right engine cover do. I'm not sure why the water pump housing was hotter than the left radiator or, the one time I measured it, the right radiator. That housing must be picking up heat from the exhaust pipe.

At Interstate speeds for about 15 minutes the gauge was showing two bars above the one for COLD, that changed to three bars as I slowed some.

The measurement was 3/4-inch at the narrow part of the pipe.

Check for leaks. If you don't find any, you are probably filling up some air voids in the system. I wouldn't worry unless the issue doesn't resolve itself fairly quickly.

Thanks for taking the measurements, and posting your data, Peter. :tup:

Thanks for posting the good link, Kat. :tup:

It seems the Thermo-Bob 3 (3/4-inch hose) is probably the best fit for the RX3. ;)

My 2015 did that too when it was new , Not enough coolant in the radiators from the factory. So I just kept adding over the next week of riding till all the air was purge. I see you've had yours awhile , so I would tighten all the radiator hose clamps . I had a little dribble from one on mine and had to look for it but it would leave a few drops on the floor after I parked it.

Fahrenheit was all the rage when I was a kid, I struggle to get my head around It these days. :hmm:

Here's a chart for us UK/Europeans

Attachment 6017

Great info peter, thanks.

An air temp of 75f is about as good as it gets in the UK. ( I remembered that temp, didn't need my chart :D ).

The evidence for "low oil temperature" is certainly building :)

After much thought I've decided to go with plan B, the homemade bypass setup.

At the moment i've ordered a thermostat housing, which includes temp sensors & thermostat, and a set of hoses from taobao.

Then when i've got measurements on the sensor holes I can order localy the bypass connectors and the hose connector bosses. Also maybe a higher temp thermostat.

This way I can hopefully get it all sorted at my leasure and keep the bike running.

If it all comes to nothing, I still have some handy spare parts.

I think that the thermobob is really the best solution but here in the UK I have to consider shipping and customs costs which will really hike the price up.

:)