CRF450R spitting coolant

[rmcmichael]

This is really my only irritant about this great bike.
It's an '03 CRF450R and it seems like it will get hot
and spit radiator fluid out really quickly. I've heard
guys say you should get a radiator cap with a higher
than stock pressure rating (mine says 1.1 atmospheres).
Sure would like to hear some opinions.

This weekend, I followed my eight year old around the
track on his Polini X-3 50cc. (First gear, idling along,
pulling the clutch in for the corners - he's just starting
out) My bike was dripping coolant about 3/4 the way
around the track. This seems a little excessive to me.

 

[Thump]

It does seem excessive.... Mine never leeks and I often follow my fiance around in the same manner as you. A couple of things to consider.
1) Your radiator cap is defective, try one off of another bike for a few laps to check, if it is get a new one. Does it boil over when you are riding at your pace? If not rule this one out.
2) Head gasket is leaking pressure into the cooling system, does it boil over when you are riding at your pace? If not rule this one out.
3) Use a good synthetic oil in the motor, I use Mobil 1 15W50
4) Run your coolant mixture with less antifreeze, more distilled water. It is more efficient for cooling 30/70 or even 20/80 mixture.
5) Go to a Kawisaki shop and order a 1.8 cap for the KX500. The KX5 standard is a 1.5 I think but they make a 1.8 too, I had to go to this on my punched out YZ400.
6) are your radiators in good shap? The CRF rads are easy to bend and if the fins don't get sufficient airflow they won't cool properly. If they are in good shape rule this one out.

Hope it helps.

 

[blackwolf001]

It's normal ; i have a 03 too and as you can heard on any forums this bike doesn't like to run on the idle or it will result in overheating and spitting coolant!!!If you want to break your head gasket , go ahead for a higher pressure cap!!!!! You can use ice coller in the radiators it will help you a little but the idea of more water and less coolant is not a good think , water is less coolant.What you can check is your jetting , if it's too lean it contributes to overheat.A good forum for the CRF450 is www.thumpertalk.com you can talk and ask about anything.
Don't compare a yamaha with an honda , they are all good but not the same technology in the engine.

 

[blackwolf001]

Sorry for the yamaha but i didn't see that you have a Honda

 

[Thump]

Blackwolf... you are mistaken about what you speak... Water DOES have better cooling properties than mix... straight water has the best of all, coolant can raise your boiling point but that does not mean it is cooler... it also acts as a lubricant this is why I said 30/70...20/80... and I have never heard of someone blowing a head gasket by running a higher pressure cap.

And you last statement of "Don't compare a yamaha with an honda , they are all good but not the same technology in the engine." it LOONY! Although the two engines differ the principles of cooling and heat transfer are the same...

 

[SFO]

I run the kx-65 cap and it is a 1.85 bar pressure rating on my 97mm yz-f and have had no problems with gaskets blowing or radiators bursting due to over pressurization. Different bikes and designs certainly but both share the same radiator manufacturer.
I notice that I get a little drooling after topping it off but that the level normally is just above the core or about 1/2" below the filler.
If it just keeps puking I would worry, but I think you might find that it will reach a level that is stable and settle down.
If you want to do a lot of low speed running you could fit a coolant recovery tank, ala wr yamaha so the spillage is recovered and will return to the radiator after it cools down some.
I hope this helps
Bill

 

[blackwolf001]

go on thumper talk , there is a thread right now speaking about it (pressure cap and head leaking)

 

[Thump]

I think I know who has a leaking head, but thanks for the offer.

 

[flynbryan]

And is the leaking head an issue of mechanic error(installation of head gasket?) of is it truely from the higher pressure? I did the above as thump has stated to my CRF w/ the more water, less antifreeze. I also got a vented front fender, and drilled holes in the engine guards, but the biggest difference for me was changing my jetting. It didn't run poorly before, but once I richened it up it ran ALOT cooler. All the changes I made to mine are fool proof and harmless. If you still don't get the results your after then maybe try the higher pressure cap. I know team honda runs these on the CRF as well as the XR's. Obviously these bikes are maintinanced more often than mine, but apparently it isn't too dangerous of a mod.

 

[Hick]

Originally posted by Thump
I think I know who has a leaking head, but thanks for the offer.

You sure know how to make a guy feel welcome around here Thump. Give the guy a break, English is obviously not his first language.

I don't know that a higher PSI cap will cause a head gasket to fail, but it would obviously increase the pressure throughout the system.

Or maybe my head is leaking. Yeah, that's it.

Sheesh.

 

[Scott Tipton]

RMC - I assume your leak is from the overflow tube, if it is I have the same problem with my 2003 450, The only thing I've done and so far and its helped, 1st I leaned out the carb setting one clip, then I installed a product called ICE in the radiatior. ICE is supposed to lower temp by as much as 50 degrees, it kind of expensive (16.00) for 1/2 gallon. Hope this helps. Oh yea i ride enduros and the only time I've had this problem is in 1st gear tight sections.

 

[rmcmichael]

No, I don't get any leakage when I'm riding my pace, just first gear trolling along at idle or just above. Thanks for the tip on jetting. I didn't think about that. I may call a few dealers and see who has what in terms
of pressure ratings on the caps. I might try something like a 1.5 atm or so. I'll look around for the ICE stuff too.

Thanks