RX3 Cooling System

[katflap]

Revotec Self Sealing Hose Take Off Kit, 8mm Barbed / Push On Fitting (SST8K)

Here's a couple more sites that ship to the USA

http://www.demon-tweeks.co.uk/Produc...FYMK0wodQlIKfw

http://www.ebay.co.uk/itm/Revotec-Se...16025#shpCntId

I still have my concerns about the size of the flange on this fitting. It could be about 21mm in diameter (0.82 of an inch), when fitted this could cause the hose to flatten out quite a bit and restrict flow.

[Watt-man]

Hi Everyone,

Interesting thread. I've read through it all and had some comments:

We've tested 1/4", 5/16" and 3/8" bypass hose sizes when doing lots of KLX250 testing, and we're a fan of the 3/8" based on the temperature stability it provides to the system.

The water pump impeller (post 10) actually spins counter-clockwise, not clockwise. It's on the counterbalancer shaft, which spins the opposite direction of the crankshaft. You do have the water flow diagram correct though - water pump pulls from bottom of right radiator, pushes coolant into block which travels up through the cylinder liner area, exits upon the side of the head, travels to your factory thermostat housing, then left radiator, then right radiator, then back to the water pump. AGREED the big issue here is there is no bypass when the bike is an any kind of cool weather, so the temperature of coolant entering the bottom of the engine is basically the same as the ambient air temperature.

We're not a big fan of plastic fittings in the cooling system, so for what it's worth all of our stuff is machined from aluminum. We hadn't seen those fittings that you can install in a hose - interesting - a tad pricey and I hope the reliability is good. They might be great, we don't know.

Given all the prices stated in post 89, you might like the idea that I've attached below. We'd generate a complete TB3 kit for the RX3, it wouldn't require any re-wiring of any sensors, it would have a 3/8" bypass line and everything would be aluminum. There would also be a spare threaded port for a KOSO or Trail Tech digital temperature gauge if anyone wanted to add one. These would be $125 complete with free shipping in the US.

You would simply remove the RX3 'stat and we'd supply an o-ring to put in its place, then reassemble the RX3 stat housing and leave it as-is. See the first photo below.

I think the question is: is there room for a Thermo-Bob 3 in the line between the existing thermostat housing and the top of the left radiator? I've attached a second picture from Spudrider that shows that particular hose, and we're thinking there's enough room in there.

As you can see in my signature, I've had a Thermo-Bob on my bike since it was new and have never torn it apart yet (just tires, chains, tires, brake pads, an occasional clutch cable)... and am already at 137,000 miles. There is a separate article at the site where we've been documenting the oil burn rate... so far, it's still doing really well. The article can be found here.

[Watt-man]

By the way, the reason we gave an option of the thermostat temperature in the Thermo-Bob 3 is because of your cooling fan switch location and activation temperature. We're used to the fan switch being in the cold side of the "last" radiator (the right radiator in your case), which works really well at identifying when the radiators aren't doing enough on their own. Since your sensor is at the bottom of the first radiator, there's a chance that a 90C (194F) stat would result in water above 82C (180F) at the bottom of that radiator during summer operation. That might take a little testing to see how a 90C 'stat works, otherwise we'll spec RX3 kits with an 80C (176F) stat which is at least better than the stock setup of 70C (158F). Time will tell if we can make the 90C stat work without making the fan run unnecessarily.

[dpl096]

Watt-man .... Great post! It's amazing to sit here and watch as this thing is being problem solved and evolving into a viable and affordable solution. All of you guys .... great work ! With each passing hour it seems this is becoming more a reality. INCREDIBLE

[Juanro]

FYI: Here in Argentina, there's a lot of these bikes that comes with a 93° fan activation switch. We're still trying to figure out is this is a case of... an improvement, or some chinese worker not paying enough attention to which box take parts of.
My bike specifically has the 82° fan switch, though.

[SpudRider]

Originally Posted by Watt-man

...I think the question is: is there room for a Thermo-Bob 3 in the line between the existing thermostat housing and the top of the left radiator? I've attached a second picture from Spudrider that shows that particular hose, and we're thinking there's enough room in there...

Thanks for joining our discussion, Watt-Man.

I have two concerns regarding the Thermo-Bob 3 (TB3) installation. The first concern regards the cramped room we have available to place a Thermo-Bob 3 (TB3) downstream from the stock thermostat housing. Besides the limited space available, the fixed wiring harness above the coolant line will also make installation of the TB3 difficult, or impossible. In addition, the process we employ to adjust the valve lash of our RX3 bikes requires us to loosen the mounts for the left radiator, and swing the radiator out of the way, in order to make enough room to adjust the exhaust valve lash. Even if we can install it, the TB3 might restrict our ability to move the left radiator fully out of the way, and further infringe on the limited space available to us for making valve adjustments.



My second concern regards the short, twisted coolant hose of the RX3 which connects the bottom of the right radiator with the water pump. I don't think we can fit your bypass tee, or any other bypass tee, into this short, twisted hose. Therefore, I think our only option is to employ the Revotec SST8K to accommodate the bypass hose.

However, I do think we might be able to fit one of your TB3 spare thermostats in our stock thermostat housing. Are you willing to sell me one of your TB3 thermostats so I can test the fitment? If the thermostat doesn't fit, can I return it to you for a refund?

I am also inclined to install a bypass tee about four inches upstream from the stock thermostat housing, and leave both temperature probes in the thermostat housing. I don't think this location of the bypass tee will adversely affect the readings of the temperature probe which feeds data to the ECU. The coolant temperature should quickly equalize over this short distance.

[rjmorel]

"My second concern regards the short, twisted coolant hose of the RX3 which connects the bottom of the right radiator with the water pump. I don't think we can fit your bypass tee, or any other bypass tee, into this short, twisted hose. Therefore, I think our only option is to employ the Revotec SST8K to accommodate the bypass hose"

Could we put a longer hose in there and loop it around somewhere and add the T? Would look like my intestines but would give the room to add T at a more convenient place. Don't have bike in front of me so maybe pump and radiator are too close?
The way bike is designed , they just don't leave any room for doodling with things like on my first Hodaka? rj

[Watt-man]

Originally Posted by SpudRider

My second concern regards the short, twisted coolant hose of the RX3 which connects the bottom of the right radiator with the water pump. I don't think we can fit your bypass tee, or any other bypass tee, into this short, twisted hose. Therefore, I think our only option is to employ the Revotec SST8K to accommodate the bypass hose.

How about shooting a couple of pictures of that hose for me. If you take the hose off, what is the physical distance from the metal tube exiting the right radiator to the metal tube at the inlet of the water pump?

Originally Posted by SpudRider

However, I do think we might be able to fit one of your TB3 spare thermostats in our stock thermostat housing. Are you willing to sell me one of your TB3 thermostats so I can test the fitment? If the thermostat doesn't fit, can I return it to you for a refund?

We are familiar with that housing... our thermostat WILL fit.

Originally Posted by SpudRider

I am also inclined to install a bypass tee about four inches upstream from the stock thermostat housing, and leave both temperature probes in the thermostat housing. I don't think this location of the bypass tee will adversely affect the readings of the temperature probe which feeds data to the ECU. The coolant temperature should quickly equalize over this short distance.

I would try to put it as close as you can to the factory housing. That area after the new bypass will have very minimal flow (because the bypass will drop the delta P of the water pump, and you have a tiny bleed hole in the thermostat) which will have both sensors lagging the actual engine temperature somewhat. Considering how we've logged actual temp climb during warm-up at 1 degree F per second, it wouldn't surprise me at all to see the sensors lagging actual temps by 30 degrees F. (as there is still hose and housing to heat, yet there is some airflow over them trying to cool them).

So let's start with the water pump inlet hose picture and see where that leads us.

[SpudRider]

Originally Posted by rjmorel

Could we put a longer hose in there and loop it around somewhere and add the T? Would look like my intestines but would give the room to add T at a more convenient place. Don't have bike in front of me so maybe pump and radiator are too close?
The way bike is designed , they just don't leave any room for doodling with things like on my first Hodaka? rj

I doubt it. The distance is short, we would need a very large, exposed loop.

[SpudRider]

Originally Posted by Watt-man

How about shooting a couple of pictures of that hose for me. If you take the hose off, what is the physical distance from the metal tube exiting the right radiator to the metal tube at the inlet of the water pump?...

I will post the photos below. The distance between metal tubes is about 1.5 inches.

Originally Posted by Watt-man

...We are familiar with that housing... our thermostat WILL fit...

That's great.

Originally Posted by Watt-man

...I would try to put it as close as you can to the factory housing. That area after the new bypass will have very minimal flow (because the bypass will drop the delta P of the water pump, and you have a tiny bleed hole in the thermostat) which will have both sensors lagging the actual engine temperature somewhat. Considering how we've logged actual temp climb during warm-up at 1 degree F per second, it wouldn't surprise me at all to see the sensors lagging actual temps by 30 degrees F. (as there is still hose and housing to heat, yet there is some airflow over them trying to cool them).

So let's start with the water pump inlet hose picture and see where that leads us.

I didn't realize your thermostats still had the bypass hole. I thought you sealed the bypass hole.

We could route the bypass hose from the port which houses the temperature probe for the digital display; it is the top port in the thermostat housing. We would need to loop the bypass hose upward before it could descend to the water pump.

Here are the photographs of the hose connecting the right radiator to the water pump. The first photograph was captured from above and behind the water pump. The radiator connection is at the top, and the water pump connection is at the bottom. As I stated earlier, there is about 1.5 inches of radiator hose between the two fittings, and it is twisted at an angle.



The second photograph was captured from below, and in front. The radiator connection is at the top, and the water pump connection is at the bottom.



The last photograph was captured from the front, just above the exhaust manifold. The radiator connection is at the top, and the water pump connection is at the bottom.

[SpudRider]

We could route the bypass hose from the port which houses the temperature probe for the digital display; it is the top port in the thermostat housing. However, we would need to loop the bypass hose upward before it could descend to the water pump.

[katflap]

Wishing to contribute a little but laptop screen is burning me eyes,

suffering with a dose of man flu at the mo.

Could be touch and go for a few days.

Should be Back on top soon

[pyoungbl]

Now the issue is where to "T" into the water pump intake hose. The water pump housing itself is cast metal, I did not check to see if ferrous or not. The snout is fairly long, maybe 2". Think about possibly drill/tap into that and avoid the short hose problem. I'm wondering about the wall thickness on the snout. Spud, if you have a spare you could measure for us.

Peter Y.

[madsocial]

I'll have my husband read the post and see if he has anything to contribute. He is a airplane/helicopter mechanic/engineer. He takes things apart all the time. I have to keep an eye on my harley or it will end up with a turbo charger.

[dpl096]

Originally Posted by katflap

Wishing to contribute a little but laptop screen is burning me eyes,

suffering with a dose of man flu at the mo.

Could be touch and go for a few days.

Should be Back on top soon

Sorry to hear you're under the weather Kat .. get well soon