Gotta a problem with a 02 650R overheating in tight trails. It is ok out in the open, any one else with this problem or corrected this problem

Hey, Potato. I've seen a radiator cap with a stiffer spring (1.6 atmospheres vs. the stock 1.1) in XRs Only catalog. Never tried it, but if mine boiled over, I'd try that first.

I think they all do(mine does) in the tight trails when the weather is hot...like here in So Cal.

Going from a 1.1(16lbs) to a 1.6(24lbs) puts a lot more pressure on the cooling system, and the radiator. I switched to Engine Ice, and it helped a bit.

Thats because the 650 was not designed as a tight trails bike :/

Originally posted by Potato:

Gotta a problem with a 02 650R overheating in tight trails. It is ok out in the open, any one else with this problem or corrected this problem

If your bike is brand new, then it will be more apt to boil over until it breaks in. If your bike is still corked up, then get used to the boiling in the slow stuff until you uncork your bike. Once your bike is broken in and uncorked (properly jetted, non-EPA intake, airbox snorkle & restrictor removed with less restrictive exhaust), then there's much less chance of your bike boiling.

Make sure your thermostat isn't sticking closed, but I doubt it as its not too common, but it still can't hurt to check it out. Some of the year 2000 XR650R's had a problem with their thermostats sticking, but it was kind of isolated from what I understand.

If your bike still boils, you can try a Kawasaki KX500 1.6 radiator cap. The Kawasaki PN# for this cap that fits the XR650R is "49085-1077" based on some notes I have kept. A higher pressure rad cap will only prolong the inevitable, but it might just get you by for your application.

There's been a few guys who have actually installed fans on their radiators and that might ad a little margin to things if you wanted to go to that extreme.

Another option is to try running a different mix of coolant like 60% water and 40% coolant.

And another option is to try adding Redline Water Wetter to your coolant, but I don't think it will buy you much.

And yet another option that's more effective is to run just plain deionized water with Redline Water Wetter and no coolant at all, but you need to stay current on the Water Wetter or else risk corrosion in your engines cooling system from the water.

The only coolant on the market that's really truly different than anything else out there is Evans NPG+, but there's several issues with this coolant that scares the heck out of many people, but I have no problems with it based on my own past personal experiences running it in various vehciles and testing I've done. This coolant always brings out a good debate when people get to talking about it :) While I use it in some of my cars, I don't yet use it in my XR650R. My XR650R does not boil over for my application, but I'll still probably be running Evans NPG+ in my bike later this year for different reasons.

Getting some miles on your bike to break it in and uncorking it with proper jetting does the trick for most people from what I know, but the subject of boiling over has been heavily discussed on various boards since the XR650R was introduced.

Had the same problem when my bike was new. Took off the CA smog sh$t, put a 1.8 cap on, hasn't boiled in the tight trails or in the So Cal desert yet. Just uncorked last week, we shall see how it runs this weekend.

Talking to the local dealer who rides 650's religously told me to install the SRC thermostat, fill the system with Engine Ice and everything will be ok. All we have to ride here in Western WA is tight trails.

I am certainly NOT sold on Engine Ice, although it sounds great when reading their marketing stuff, but I don't see how it could be much better than Honda HP coolant or any major brand of coolant for that matter that costs a whole lot less, especially when it comes to solving boiling issues on our XR650R's. I've spoke with a few guys that have tried Engine Ice on their XR650R's and they still boiled just as easily as before.

In fact, its been concluded by the SAE (Society of Automotive Engineers) that the most effective coolants in transferring heat in their tests was 100% water, followed by 50/50 ethylene glycol/water, followed by 50/50 propylene glycol/water, followed by 70/30 ethylene glycol/water, followed by 70/30 propylene glycol and finally 100% propylene glycol. Engine Ice is propylene glycol based coolant, so judge this for yourself. You can reference SAE paper 960372 for this information and more.

Just take a look at the technical specs of EG & PG based coolants and you'll see that many of the most important factors actually favor EG based coolants. The fact is that EG has better thermal conductivity, better density, lower viscosity and anyone can check this out for their self by doing a little homework. On the other hand, PG is less toxic than EG ‘before’ it’s put into an engine, but it’s definitely contaminated after it comes out of an engine, thus making the toxicity issue carry a lot less weight in my mind. From what I’ve read, PG allows a more efficient heat transfer from the metal to the coolant at higher temperatures when nucleate boiling occurs, but depending on how much (if any) nucleate boiling is occurring, then PG may or may not be more efficient in this respect. For normal use it appears to me that EG based coolants have a slight advantage in terms of overall cooling performance except for pure water of course which outperforms them all. Here’s some hard numbers I have in my notes to look at for comparing PG, EG & water, all of which are based on a temperature of 120F.

Thermal Conductivity [bTU/(hr*ft^2)(F/ft)]

EG/H2O = 0.230

PG/H2O = 0.217

H2O = 0.37

Note: Larger numbers mean faster heat transfer. While it should be obvious that lower numbers mean the fluid will absorb heat more slowly, make note that it will also give up the heat more slowly.

Specific Heat [bTU/lb*F]

EG/H2O = 0.811

PG/H2O = 0.871

H2O = 1.00

Note: Larger numbers mean that it takes less energy to raise the temperature of a given mass of fluid. The higher the number, the more energy the fluid can carry away for a given rise in temperature. In other words, this number says how much heat the fluid can hold.

Viscosity [cP]

EG/H2O = 1.8

PG/H2O = 2.3

H2O = 0.5

Note: Smaller numbers are better and assist heat transfer, but the effect of viscosity is most significant at lower temperatures from what I’ve read.

Denisty [gm/ml]

EG/H2O = 1.03

PG/H2O = 1.01

H2O = 1.00

Note: Higher density numbers are better and mean that the fluid is able to carry away more energy due to a higher mass flow.

I personally don't see how Engine Ice coolant will allow an engine to run any cooler than Honda HP coolant or any other name brand coolant for that matter. I’m sure Engine Ice is a fine product, but so is Honda HP, Dex-Cool, etc, and most are a lot less expensive than Engine Ice. Just make sure you use a non-silicate anti-freeze in your bike because the silicates can cause problems with your seals. Pure water with a surfactant like Redline Water Wetter will cool better than any EG or PG based coolant, but you'll have to change it regularly to keep your system clean and minimize corrision. I don't like the maintenance of running just water, so I run an EG based antifreeze and I don't have any boiling issues for my XR650R applications.

I guess I'm just lucky but my uncorked 650R has never boiled over. I almost didn't buy this bike because of all the horror stories(CS seal,clutch bushing,overheating,poor handling in the tight stuff)but I have ridden over 1800 miles since early June with zero problems. If only I could keep a rear tire on it for more than 400 miles I would have no complaints at all. :)

Mine's uncorked, I ride in tight woods all the time, no overheating issues yet. Lean mixtures fight smog at the expense of temp. - my guess is that it's the mixture.

I was going to head up to an area running a race, and they made a big deal about running EG, and I was having problems with a little boil-over, so I switched to the Engine Ice(PG) so I wouldn't have to listen to the eco-freaks whine, and have had little problems with boil-over, but it's not some holy-grail of the coolant world. A little boil-over now and then isn't a problem, except if you removed the coolant overflow bottle. I can tell if my bikes running hot, by looking down at the bottle, if the levels up, then I running hot, but, as the bike cools, the level drops back to normal.

Great Thanks for all the info. I think I will try the jetting first.

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