RX3 Cooling System

[pyoungbl]

Originally Posted by rjmorel

So use your boring bar to bore that puppy out to a 450cc, I'd buy one . That was a machinist joke, I know it's not doable but what the hey, from one machinist to another, rj

Great idea! I think I still have a piston out of a Ducati 1000DS so I can just turn it down a RCH (technical turn used in a machine shop) and Bob's your Uncle! At the same time I think it best to go ahead and install hydraulic lifters since it is such a PITA to get to the exhaust side. Oh, darn, then I need to move the cam. OK, moved the cam and installed variable valve timing (VVT). Now I have just over 1000 man hours, 45 cases of beer, and about $5K invested in mods for a bike that will almost keep up with a KTM 390. Makes perfect sense to me.

[katflap]

Originally Posted by pyoungbl

Katflap, I have been dying for an excuse to use a boreing bar on my mill, looks like you have opened up an opportunity for me.

Good stuff, get some use out of that kit

Unfortunately I have to take a more low tech approach with a mini grinder attached to my drill. It should be a fairly swift job as its only made of an alloy.

[katflap]

Originally Posted by Watt-man

Here's a plus: note that the RX3 stat has a 2mm bleed hole in the stat, I specify mine with 1mm. You'd be surprised how a large bleed hole delays warm up and lowers operating temps in the cooler weather... the double-sized bleed hole has 4 times the area, and more than 4 times the flow because of boundary-layer effects. When it's cool outside (or you're warming up), you want the radiator bypassed as much as possible!

Yes, the size difference is even more noticeable in the "flesh" .

Definitely an extra bonus

[rjmorel]

Originally Posted by pyoungbl

Great idea! I think I still have a piston out of a Ducati 1000DS so I can just turn it down a RCH (technical turn used in a machine shop) and Bob's your Uncle! At the same time I think it best to go ahead and install hydraulic lifters since it is such a PITA to get to the exhaust side. Oh, darn, then I need to move the cam. OK, moved the cam and installed variable valve timing (VVT). Now I have just over 1000 man hours, 45 cases of beer, and about $5K invested in mods for a bike that will almost keep up with a KTM 390. Makes perfect sense to me.

OK ,I'll bite, Whats RCH mean? rj

[pyoungbl]

PM sent, not recommended for all audiences.

[katflap]

Originally Posted by katflap

My new thermostat from watt-man.

The dimensions of the new stat are not quite the same as the original. The stat is a little shorter, this isn't a problem. The base of the stat ( where the temp rating is stamped) is a little wider.
Unfortunately this extra width stops the stat sitting flush in the thermostat housing.

The good news,

I think, by removing about 1.5mm from the width and to a depth of about 3mm from the curved fillet in the thermostat housing (see pic) and all should fit nicely and it should be pretty easy to do

Hoping to have time to fit it this weekend

As anticipated, it only took 5 mins to grind the thermostat housing so the new stat (85c) fitted correctly.
Once fitted I took the bike on Its usuall test ride. Got Some good temp readings 75c - 80c.

I did notice when going down a hill the temp did drop back to 70c but once on the flat with a bit of throttle it came back up to 77c very quickly.

When riding at 7000rpm in 6th the temp builds nicely and probably would
of hit 85c If I had continued at this speed for long enough.

As watt-man said, the smaller bleed hole works brilliantly, I have a thermostat radiator cap so I can monitor the temp down stream of the thermostat. The difference compared to the stock thermostat is very noticeable.

When stationary the fans kicked in at about 86c once the thermostat opened and did there job perfectly.


So that's it for me, I will be leaving it at that for now.

I'm really happy with the temperature results and the fact that the bike does seem to like this by-pass is another bonus.

The real test will be when the winter comes.

[pyoungbl]

Katflap, is your bypass 3/8"? Did you notice a quicker warm-up? What would you do differently were you to do this again?

I have the 190F 'stat incoming but won't get to install for at least a month.

[katflap]

Originally Posted by pyoungbl

Katflap, is your bypass 3/8"?

No, my connectors for the bypass has an I.D. of 5mm, I think that converts to aprox 3/16", and my bypass tube has an I.D. of 8mm.

Originally Posted by pyoungbl

Did you notice a quicker warm-up?

I've yet to use the bike from cold. I set off on my test run straight after re filling the coolant.
To get as much air out of the system as I could I ran the bike with the rad cap off, topping up and squeezing the hoses. It was already at 75c by the time I had finished.

Will let you know when I have

Originally Posted by pyoungbl

What would you do differently were you to do this again?

Probably not a lot as I didn't want the cost to spiral out of control.

I took a gamble with the size of the of the self sealing barb. This pretty much set the size of my bypass.

I think now, seeing the barb fitted, I might of been able to use a larger one.

The small size of my bypass made me cautious of using the 190f stat, just in case there wasn't enough flow.

Originally Posted by pyoungbl

I have the 190F 'stat incoming but won't get to install for at least a month.

I'm looking forward to your results. I think the 190f stat will be fine with your 3/8" bypass.

If I had the tools I would of tried to do a bypass like yours.
But if watt-man had a "plug n play" thermobob & bypass ready for the RX3 I probably would have bought that

[katflap]

Originally Posted by pyoungbl

Katflap, Did you notice a quicker warm-up?

Originally Posted by katflap

I've yet to use the bike from cold. I set off on my test run straight after re filling the coolant.
To get as much air out of the system as I could I ran the bike with the rad cap off, topping up and squeezing the hoses. It was already at 75c by the time I had finished.
Will let you know when I have

Have now tested.

Yes, during warm up at the same point in my ride to work,

Original stat = 54c

new stat = 68c

[Jay In Milpitas]

Thanks for your research & results, Katflap.

1/4 inch is a bit more than 6mm, 5mm is a touch bigger than 3/16 inch, for those curious about the conversion.

[BlackBike]

68 .....that 154.4F in dog years

[pyoungbl]

I have ordered two thermostat housings through Taobaotrends....two so I can screw up one and still finish the project. There have been some comments about shipping cost, that shipping was going to be expensive. Well, I just got the shipping quote for the two parts and I'm happy to see it's only $9.00! USPS to California is at least that much. The process is a little awkward at first but now I understand their web interface and all is good.

[katflap]

$9.00 shipping for 2 thermostat housings is excellent.

Though I guess shipping costs do differ from country to country.

Taobaotrends have always provided me with an excellent service. I like particularly bieng able to use paypal and also that they show you photos of the actual parts they have received so that you can be sure you've ordered the right stuff.

-----------------------------------------

[pyoungbl]

Katflap, et al:
I'm back from my summer Walkabout (Stelvio, 7500 miles) and ready to attack the Zong over cooling issue. When last we met I had tapped a spare water pump housing for a 3/8" barbed fitting so I could rig up a bypass from the thermostat housing. In the last couple days I did a similar job on the thermostat housing. As I tried to re-assemble all this I discovered that my bypass hose is going to pass so close to the exhaust pipe that it's bound to fail. Literally, touching the pipe. As I study the pump housing it's hard to find a way around this problem. Thus, I put everything back together. I did install a 90C thermostat from Wattman (had to mill out a small bit of the thermostat housing) and I enlarged the air bleed hole in the thermostat just a tiny amount. I'll check the engine temps once I have everything buttoned up and report back.

Peter Y.

[pyoungbl]

Hi Campfire friends, I finally took the mighty Zong out for a spin just to see what changed now that I have installed a 90C thermostat. On a day when it was 87F the left radiator started out at 86F. In 5 minutes of getting dressed time that went to 128F, after 15 minutes of stop and go traffic that was up to 202F and after a very short bit of Interstate and back to the garage the temp was 171F. At the oil sight glass the temps were 84, 88, 172, and 197. I conclude that the engine is getting to a higher temp, almost enough to boil off water and most likely well over the temp needed to get rid of fuel. I'd say we have more than enough cooling for really hot days and the hotter thermostat warms up the engine faster. Only an oil analysis can tell if this reduces the % fuel in the oil, I am very hopeful.

Peter Y.