RX3 Cooling System

[katflap]

Originally Posted by pyoungbl

kat, I'm not a KLR owner but at one time did lots of research thinking that I might want to get one. The KLRs had a few systemic problems, all of which have been addressed by aftermarket products. The cooling system is very similar to our Zong. The KLRs were noted for always running cool and some had serious oil burning problems that were blamed on uneven cooling. There was no rad bypass so hot spots would develop, then get a slug of cold coolant, then heat back up. The Thermobob seems to have solved that problem so it's a very popular mod. With all that said, waddya think of a simple bypass between the head and the thermostat housing and going to the water pump intake? That would give some actual circulation as the engine warms up and, once the thermostat opens, slow down the circulation through the radiator so the rad could shed more heat if needed.

That's interesting to know about the KLR. Thanks

regarding fitting a bypass , I was thinking a similar thing and perhaps having an inline tap in the bypass tube to gain some control of the flow.

There could be a problem though, the ECU relies heavily on the temp sensor in the thermostat housing. by introducing a small bypass it could upset the balance between actual engine temp and recorded temp from the sensor in the housing. this is just guess work on my part

I'm still tempted to have a play with this though

[pyoungbl]

Originally Posted by katflap

the ECU relies heavily on the temp sensor in the thermostat housing. by introducing a small bypass it could upset the balance between actual engine temp and recorded temp from the sensor in the housing. this is just guess work on my part

Well, I was thinking that if the bypass were close to the thermostat (and sensors) it would be a moot point or maybe actually get the true engine temp to the sensor sooner. As it is, the temp sensor works off the coolant that is trapped in the thermostat housing. Except for the small bleed hole on the thermostat, the housing is a dead end for coolant flow until the thermostat opens. The temp sensor actually lags behind the actual temp during warm-up. If I had that housing I'd want to see if I could drill and tap for a bypass spigot. At the same time I'd like to see if a different thermostat would fit (what Spud mentioned).

[katflap]

Originally Posted by pyoungbl

Well, I was thinking that if the bypass were close to the thermostat (and sensors) it would be a moot point or maybe actually get the true engine temp to the sensor sooner. As it is, the temp sensor works off the coolant that is trapped in the thermostat housing. Except for the small bleed hole on the thermostat, the housing is a dead end for coolant flow until the thermostat opens. The temp sensor actually lags behind the actual temp during warm-up.
If I had that housing I'd want to see if I could drill and tap for a bypass spigot. At the same time I'd like to see if a different thermostat would fit (what Spud mentioned).

Great idea , a spigot directly into the thermostat housing , I think your right, that would do the trick, brilliant

Think I might have to purchase a spare thermostat housing to play with

[detours]

I'm very interested in this mod but have almost nothing to add to this thread except a link to the Thermo-bob page:

http://shop.watt-man.com/Thermo-Bobs_c4.htm

FAQ - http://www.watt-man.com/Information__Articles.html

[dpl096]

Good thread and very interesting mod. If the ECU is receiving more accurate information might that better affect the mixtures and partially clear up the OCS issue? ? ?

[SpudRider]

After doing a bit of research, I see the stock thermostat in the KLR650 is removed during the installation of the Thermo-Bob. The Thermo-Bob bypass includes an automotive thermostat set for a higher temperature. The Thermo-Bob allows coolant to circulate bypassing the radiators before its thermostat opens. The early flow of coolant in the Thermo-Bob bypass is designed to allow the engine to reach ideal operating temperature more quickly, and to prevent the coolant from forming hot spots in the cylinder.

[detours]

They make a 3rd gen Thermo-bob for the Ninja 250 that might work for the RX3. It looks like it connects inline instead of bolting on, but I could be misunderstanding the diagrams.

http://shop.watt-man.com/Thermo-Bob-...-YEARS-TBN.htm

Spud, I think that's how it works. When the engine is cold, the bypass allows warm coolant to warm the engine faster. The second thermostat in the Thermo-bob closes the bypass at 195 degrees, so the radiators can do their job. This keeps the engine at a steady 185-195 degrees F, so water and fuel can vaporize and exit the crankcase.

[SpudRider]

As usual, thanks for posting the great information, amigo.

I found the following webpage which describes the operation and design of the Thermo-Bob. This webpage duplicates your information, but adds the missing piece of information I was seeking.

http://www.watt-man.com/uploads/TB_Testing.pdf

The bypass line does not contain a thermostat. The original thermostat is removed, and an automotive thermostat, with a higher opening temperature, is contained within the Thermo-Bob. The bypass line is located upstream of the thermostat in the Thermo-Bob. This bypass line is always open, since it does not contain a thermostat. However, the bypass line is much smaller in diameter than the main radiator line. Therefore, the bypass line is more restrictive, and is mostly bypassed after the thermostat in the Thermo-Bob itself opens.

[katflap]

Thanks detours, excellent info

I will definitely be taking a closer look at the thermobob. I wonder if the hose size connections are the same as the RX3.

I think we would have to remove the thermostat from our RX3 thermostat housing and then connect it somewhere between the cylinder head and the thermobob. By doing this our temp sensors will then be before the thermostat, where they need to be

[SpudRider]

Originally Posted by pyoungbl

Well, I was thinking that if the bypass were close to the thermostat (and sensors) it would be a moot point or maybe actually get the true engine temp to the sensor sooner. As it is, the temp sensor works off the coolant that is trapped in the thermostat housing. Except for the small bleed hole on the thermostat, the housing is a dead end for coolant flow until the thermostat opens. The temp sensor actually lags behind the actual temp during warm-up. If I had that housing I'd want to see if I could drill and tap for a bypass spigot. At the same time I'd like to see if a different thermostat would fit (what Spud mentioned).

Originally Posted by katflap

Great idea , a spigot directly into the thermostat housing , I think your right, that would do the trick, brilliant

Think I might have to purchase a spare thermostat housing to play with

This system would work well, but it depends on two variables.

1. The stock thermostat housing needs to be able to accommodate a fitting for the bypass hose.

2. The short hose with the tight bend, which connects the radiator to the inlet of the water pump, also needs to be able to accommodate a fitting for the bypass hose.

Ideally, we should also find a thermostat with a higher operating temperature (195 degree Fahrenheit), which fits inside the stock thermostat housing. However, the bypass itself would still be an improvement, even with the stock thermostat.

[katflap]

I have been having a look at a home made bypass solution based on peters excellent idea.

By removing one of our temp sensors from the thermostat housing it maybe possible to screw in a bypass connection in its place.
Then refit the temp sensor in the boss of a connector.

One problem is that the parts to make this might not be a lot cheaper than just buying the thermobob.

[SpudRider]

Originally Posted by katflap

Thanks detours, excellent info

I will definitely be taking a closer look at the thermobob. I wonder if the hose size connections are the same as the RX3.

I think we would have to remove the thermostat from our RX3 thermostat housing and then connect it somewhere between the cylinder head and the thermobob. By doing this our temp sensors will then be before the thermostat, where they need to be

You're right, Kat.

We could remove the stock thermostat, and relocate the stock thermostat housing closer to the outlet from the cylinder head. Then we could place the Thermo-Bob downstream from the stock thermostat housing, somewhere near the original location of the stock thermostat housing.

Of course, we do need to contact Watt-man, and see if any of his different Thermo-Bob kits will fit the hoses of the RX3.

[SpudRider]

Originally Posted by katflap

I have been having a look at a home made bypass solution based on peters excellent idea.

By removing one of our temp sensors from the thermostat housing it maybe possible to screw in a bypass connection in its place.
Then refit the temp sensor in the boss of a connector.

One problem is that the parts to make this might not be a lot cheaper than just buying the thermobob.

Attachment 5998

This is ingenious, but I like your first idea better.

Even if we relocate the stock thermostat housing, and install a Thermo-Bob downstream from it, I think we would still need to fit some type of adapter to accommodate the short hose with the tight bend which connects the right radiator to the water pump housing.

[katflap]

Originally Posted by SpudRider

This is ingenious, but I like your first idea better.

Even if we relocate the stock thermostat housing, and install a Thermo-Bob downstream from it, I think we would still need to fit some type of adapter to accommodate the short hose with the tight bend which connects the right radiator to the water pump housing.

I think your right spud,

Its going to take a bit of faffing, possibly with adapters, to get all to fit nicely

[katflap]

Here's a link to a pdf giving, amongst other things, the hose size for the thermobob 3.

http://www.watt-man.com/uploads/What...ent_Thermo.pdf

It says that there is a 5/8 inch and 3/4 inch available.

1/ what's this " old money "stuff, where's the metric

2/ I've no idea what the internal diameter of our hoses are