RX3 Cooling System

[katflap]

Thats some good temps your geting there Peter.

I think your idea of enlarging the air bleed hole to allow a little more circulation when the themostat is shut is perhaps the way to go.

Though my bike has been running really well with the higher temps I'm starting to think that my bypass might perhaps be unecessary. I have noticed on some cooler days that the coolant temp has started to drop away.
I plan to put an inline tap in my bypass pipe and experiment with ajusting the flow through it.

I agree, the coolant system is certainly able to cope with no problem. I wonder if its cooling capacity is in fact too large.

[pyoungbl]

Kat, the air bleed hole on Wattman's thermostat is tiny. I should have tried to measure it by using a very small drill bit. The thermostat itself is so small that it's hard to enlarge that hole much, not much metal to remove without damaging the 'stat. Even with the slightly larger hole it took a few heat/cool cycles to get air out of the system. I'm not sure the hole makes any real difference with cooling but it is bound to help when bleeding the system. It is important to install the thermostat with the hole 'up'.

[katflap]

Originally Posted by pyoungbl

Kat, the air bleed hole on Wattman's thermostat is tiny. I should have tried to measure it by using a very small drill bit. The thermostat itself is so small that it's hard to enlarge that hole much, not much metal to remove without damaging the 'stat. Even with the slightly larger hole it took a few heat/cool cycles to get air out of the system. I'm not sure the hole makes any real difference with cooling but it is bound to help when bleeding the system. It is important to install the thermostat with the hole 'up'.

yeah, With my wattmans 85c thermostat that has it original sized hole , very liitle flow appears to get through. My coolant temp gauge can read 75c whilst my radiator cap temp gauge can be as low as 20c. Admittedly by the time it has reached my rad cap guage the coolant has passed through one radiator.

I remembered, when fitting, to point the hole up

At these higher temps my bike seems to run smoother less "snatchy", no stalling, less collection in the OCS tube and a slightly improved fuel consumption. Though i think the winter will be the true test.

I would be amazed if running at these higher temps didn't get rid of most of the fuel contamination in the oil.

[pyoungbl]

Today I got to run the bike for two hours, mostly at 45-55 mph, in 90F ambient temps. When I stopped the oil sight glass was 216F. That was higher than either radiator or the water pump inlet. This tells me that I'm finally getting the oil hot enough to boil off water and fuel. The temp gauge never got above 4 bars.

Peter Y.

[Azhule]

Originally Posted by pyoungbl

The temp gauge never got above 4 bars.

Peter Y.

Where does the Temp Sensor on the RX3 read off of? (Cylinder head temps? Radiator/Thermostat Temps?)

[katflap]

Originally Posted by Azhule

Where does the Temp Sensor on the RX3 read off of? (Cylinder head temps? Radiator/Thermostat Temps?)

Thermostat Housing

[jbfla]

Originally Posted by pyoungbl

Today I got to run the bike for two hours, mostly at 45-55 mph, in 90F ambient temps. When I stopped the oil sight glass was 216F. That was higher than either radiator or the water pump inlet. This tells me that I'm finally getting the oil hot enough to boil off water and fuel. The temp gauge never got above 4 bars.

Peter Y.

Peter,

As I remember, you had to modify the thermostat housing. Is that correct?

Any chance there may be a "drop-in" replacement thermostat?

jb

[pyoungbl]

jb, the thermostat from Wattman is the same diameter as OEM but extends farther down into the housing.

you will find that there is a 'ledge' inside the thermostat housing

that ledge is just large enough to keep the thermostat from seating all the way. I milled some of the ledge away and the new 'stat dropped right in.


I have a spare thermostat housing and could easily mill it out for you if you decide to make the switch. As for getting a drop in thermostat...you'll have to do your own research there.

Peter Y.

[jbfla]

Originally Posted by pyoungbl

.......

I have a spare thermostat housing and could easily mill it out for you if you decide to make the switch. As for getting a drop in thermostat...you'll have to do your own research there.

Peter Y.

Peter, sending you a pm.

jb

[katflap]

Originally Posted by katflap

Though my bike has been running really well with the higher temps I'm starting to think that my bypass might perhaps be unecessary. I have noticed on some cooler days that the coolant temp has started to drop away.
I plan to put an inline tap in my bypass pipe and experiment with ajusting the flow through it.

I have now had a little play with this but rather than use an inline tap, I used a hose clamp and closed off my bypass tube.

By doing this it didn't raise the coolant temp as I thought it might.

What i did notice is that the coolant temperature was less stable especially during warm up and also that the right hand radiator (with rad cap) warmed up alot more than before.

I now think that though the bypass tube may not be essential it is certainly desirable.

If I now wish to raise the coolant temp further I will have to upgrade from a 85c to a 90c thermostat and/or make a bypass system with a bigger internal diameter

[katflap]

Now the days are getting cooler I have noticed that my coolant temp has started to drop below what I would like.

So I have made some radiator covers to bring the coolant temp back up to a better level.
They only took 10mins to make, (kind of self evident ), out of an old inner tube. They can be easily removed, without tools, as and when required.

I tested them today, the air temp was 14c-16c (57f-60f) and successfully increased my coolant temp, keeping it at between 74c-80c (165f-176f) whilst riding.

There is still a reasonable cooling effect from just the air flow over the engine, this is more noticeable when riding downhill.

When stationary, at these air temps, the fans are still able to draw enough cool air through the radiators to reduce the coolant temp and stop the engine overheating.

[katflap]

70c and 85c Thermostat comparison

Though, unfortunately not an exact comparison



Both graphs are a 10-15 min trip of the same route. At a starting temp of approx.25c.


Graph 1 (coolant temp 1), is the 70c stat, this trip was made in the summer with an air temp of between 15c and 20c.

Graph 2 ( coolant temp 2), is the 85c stat, this trip was made recently with an air temp of 7c.



Other differences for graph2 is that I have a thermostat bypass fitted and also radiator covers.

The bypass probably accounts for the smoother graph line.



With the hotter stat, I have noticed a decrease in fuel consumption, gaining an approx. 20miles per 8 or 9 litres.
That said, I removed my top box at the same time as changing the stat. This could influence the fuel economy.



Why does the temp never reach the thermostat rating ?

My guess is that the cooling system is too large

[pyoungbl]

Man, you can clearly see that the thermostat is opening ...shooting a slug of cold water into the engine...then closing to heat the water...and opening again. In my mind it is much better to reach a stable temp and stay there, like you have with the bypass fitted.

[katflap]

Originally Posted by pyoungbl

Man, you can clearly see that the thermostat is opening ...shooting a slug of cold water into the engine...then closing to heat the water...and opening again. In my mind it is much better to reach a stable temp and stay there, like you have with the bypass fitted.

yeah, I does seem to be the case. But I don't understand why the thermostat is opening at such a low temperature.

I will look further into the logs and get back to you with probably some "half baked" theories as to why this is happening

[Jay In Milpitas]

Originally Posted by katflap

yeah, I does seem to be the case. But I don't understand why the thermostat is opening at such a low temperature.

I will look further into the logs and get back to you with probably some "half baked" theories as to why this is happening

If you are taking the temp from the stock sensor, it's at the "out" end of the first radiator, so it's already been cooled some.