radiator guards...cont.

i destroyed my left radiator guard over the weekend. it did its job since my radiator survived but it's time for a new set.

i was using the works connection guards. i would like to run a set that gives the front of the radiator protection since a lot of my radiator work and replacement comes in the form of core shots.

i need protection up front but have never run the full guards like the devols due to fear of restricting air flow to an already heavy breathing high temp. running bike like the 650r.

are you guys running full guards like the devol set? what else is out there? have you noticed a tendancy for boil over or any bad side effects from running the full guards.

like i said, i have way too many core shots not to run something up front but have been too afraid to restrict airflow...

i ran the devols. i was concerned with overheating, but it never happened with them. crashed hard and broke a devol, but the radiator was intact-guess they work!

I now run the hyflow radiators (IMS) they are superb--but sadly the Devol guards wont fit--i might modify or just make a custom set to protect the front from rock hits.

I had to modify the Devols a bit originally to get them on as they are made for a corked bike-but no big deal to do that.

just my 2 pesos worth... :thumbsup:

thanks irondude.

i know you run a lot of score and bitd races... and you said you never noticed an issue with the decreased airflow, but what about in canyons or on goat trails?

my concern is when the trails slow down, i.e. in d37 for the enduros or nationals they will run us through a lot of sections that already put the bike on the verge of boil over... i'm afraid the devols will send it over the edge.

when you ran the devols did you have the bike in a lot of situations where boil over became a possibility...say while practice riding?

but like i said, i run off the ribbon and am taking way too many chances with core shots.

i already have eric at fontana radiator works programmed into my speed dial and it's getting a little old.

of course i could just work on picking better lines. :thumbsup:

i've done lots of tight stuff on the bike. Tecate Hair Scrambles, i ironmaned Laughlin with the Devols-- only got into 3rd gear 3-4 times in 5 hours!

Tim Morten swears the overheating is just the amount of clutch used on the 650. IN recent Baja trips thru Tim's excellent single track routes I've been working on keeping the throttle open at very low revs thru the nasty tight stuff-and just grunting it. I stall it now and then, but for the most part it does well-great traction-and not using the clutch does seem to help-until i catch the slower riders going up a single track hill!!!

I dont know what the best solution is for the overheating-waterwetter is gonna bring down the temps considerably, a colder plug seems to help as well-i run the 8. theres other things to do as well-like a fan-but i havent tried that (yet). Bigger radiators is my insurance-a BD dipstick temp guage would probably help define the problem a bit-its on my list...

anyway--mine didnt overheat with the devols on.

Hope that helps!

thanks irondude. i'll give em a whirl, based on your advice.

well said on the technique. i rode an enduro yesterday and my one goal all day was to stay off the clutch. i didn't care how much time i thought i would lose or chance stalling. i went for it and stayed off the clutch...big difference. it was one of the first times where i finished a major technical section and felt like i had a fresh clutch. next race my goal is to stay off the front brakes. i'm thinking about moving the lever a little out of reach. lol.

waterwetter: what's that? i've run hondaline rad fluid but will try something new.

what about engine ice. what's your thoughts? i applied for a sponsorship from em but wonder who else has run the stuff in their 650s...

I use Devol guards as well. Ride mostly tight stuff in Arizona(2nd and 3rd gear). They work great with no overheating.

Have taken many soil/cactus/tree samples with no rad problems.

Only time I have boiled-over was on a gnarly up-hill, waiting for KTM's to get out of the way, using tons of clutch. :thumbsup:

That's good to hear about the Devols because I was a bit worried about overheating with them as well, but since I switched to Evans NPG+ a few years ago, boiling over hasn't an issue for me even when letting my bike idle stationary for 15 minutes or while riding in 1st gear with small kids in the desert during the summer, etc. I've been running the Works Connection braces for a few years and they've worked pretty well, but the front of my rads have taken a beating and they don't look pretty anymore. The cactus, scrub & yucca really takes its tole on the plastic and there's always stuff stuck in my radiators.


How about a quick write up on the pros and cons of varioius radiator fluids---Evans, WaterWetter, Engine Ice, others...You know all about everything :thumbsup:

yeah, EI dave seems like a pretty good guy. i've gotten to know his online persona on another board. he knows his stuff. when it comes to coolent and radiators i think he is doing more than just selling water.

just don't ever get into an argument with him about politics, the war, gay marriage, people putting assorted objects in their butts, facism, gun control, the south, florida, other messageboards, track suers, bubba stewart, scooters, smoking, rush, europe, the future of supercross, etc. :thumbsup:


How about a quick write up on the pros and cons of varioius radiator fluids---Evans, WaterWetter, Engine Ice, others...

I don’t think there’s one single coolant that’s the best for every bike and every application, but some are better than others, especially if you’re looking at using coolants from you local auto parts store. The main thing you want to stay away from is a coolant with silicates. Some traditional automotive coolants use silicates to provide general corrosion protection for aluminum cooling systems and to act as a deterrent to cavitation, but the silicates have their own set of problems including being abrasive. After a while the silicates will separate and drop out of the coolant, which can lead to further problems (plugging up passages, etc). These traditional coolants are typically dyed green in color (the stock Honda coolant inside our bikes is one exception) and you should not use them in your bike.

We want a low or preferably non-silicate based coolant that's specifically designed for aluminum engines and these coolants are typically orange or red in color. You can buy them from your local auto parts store, but again, you have to know what you're doing because there's more to the story than meets the eye. I don’t want to go into a ton of detail, but in short, I’d recommend to stay clear from Dex-Cool, but you can google around to find more info about Dex-Cool details if you want to.

Another very important point concerns non pre-mixed coolants. Do not mix your coolant with tap water or other waters that are filled with minerals, sodium, chlorine, etc. Only use pure water if you want the best results and minimal problems down the road. If you're unsure of which automotive coolants to use, then stick with the recommended coolant that's outlined in your manual and you won't go wrong with that (Honda HP coolant is a good coolant). One automotive coolant that comes to mind which works well in our bikes is the red Toyota coolant which is good stuff .

The SAE (Society of Automotive Engineers) has done all kinds of testing on coolants and they concluded that the most effective coolant 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. You can reference SAE paper 960372 for this information and much more.

If you take a look at the technical specs of EG & PG based coolants, 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, but then you’re stuck with the limitations of water, which means you’re more subject to corrosion, fouling, microbiological growth, freezing, etc. 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.

Some race tracks require that you use a certain type of coolant, so you may be limited in your choices, but I just ride for recreation now days and get to pick anything I want. I never had an issue boiling over with my 650R until I parked it on the side of a trail with the engine running during the summer while helping out a downed rider. In the following weeks, I became the guy who took out all the little kids on 30’s & 50’s for trail rides and my bike would sometimes boil over in similar circumstances when leaving my bike running while helping out the little kids, but never while riding with my friends or during normal circumstances and the stock Honda HP coolant would have done me just fine for my normal riding needs. In any case, I knew about Evans because I had been running it in several vehicles I own for a number of years that typically sit in storage for long periods of time since I’m no longer racing them. Evans has some attractive properties, but there are some things that are not so attractive about it.

A few years ago I was initially curious and a bit concerned how the Evans NPG+ would work in my bike, so I drilled and tapped one of the frame plugs & the water pump housing for 1/8 NPT to use with some thermistors so I could monitor & data log the oil & coolant temperatures while riding. I rode during the summer months on slow desert trails, dunes, etc, and never had my temperatures get out of check with the NPG+. I’ve been running it for a few years in my bike with good results and everything inside is still bright and shiny. We’ve also been running it in a few other bikes with good results, but I only monitored temps for a short while in my bike and not the others. There’s also been at least a half dozen other 650R riders in the Yahoo XR650R group who have been using NPG+ for a few years with good results.

One of the good points of Evans NPG+ in my opinion is the higher boiling point. A higher boiling point does not mean the engine temperature will reach those high levels, but it does mean the coolant will be doing its job up until that point. Once the coolant starts to boil, then it’s no longer in contact with the metal. The vapor from internal boiling further insulates the coolant form the metal and any hot spots inside the combustion chamber only get hotter because of this and the temperature can rapidly climb to unsafe levels if things don’t get back in check quick enough. The Evans NPG+ is more vicious than a water based coolant; doesn’t flow as well and doesn’t remove heat as well as a 50/50 mix, but it continues to work when the 50/50 mix fails and that was important to me. The Evans NPG+ is also considered a lifetime coolant in that it contains no water, so the chances of corrosion, microbiological growth, etc, are greatly reduced. The cars I have in storage with standard coolants all have leaking seals with corrosion around the water pump, corrosion inside the radiators, etc, where as the vehicles that have Evans NPG+ still look as good as the day I poured it in from years ago. Also, because of the higher boiling point with NPG+, you don’t have to run pressure in your system and therefore your seals & hoses aren’t stressed nearly as much as if you were to use a high pressure radiator cap as some folks do when trying to minimize boiling issues. The NPG+ is a waterless coolant and you may be screwed out in the desert or out on the trail if you somehow loose coolant because you cannot simply add water from your hydration pack into the system like you can with most coolants. For me it’s not a big deal because I’ve never had a leak and I also carry extra NPG+ in my trailer just incase, but if you’re racing Baja and damage a radiator, I doubt the local village will have Evans coolant near by.

You can mix any non-silicate coolant to favor certain properties, but Evans NPG+ is the only coolant I know of that’s a lifetime coolant, runs without pressure and has the high boiling point which is what I was looking for. When you look at the thermal conductivity, specific heat, & viscosity properties of various coolants, water looks very attractive if you can live with its limitations such as a lower boiling point, issues concerning freezing, no corrosion protection, much more frequent maintenance, etc. Water however is safe for the environment and easily cleans up and or evaporates after a spill, so you also have to weigh those advantages for your needs. Water Wetter is a surfactant that can be added to pure water or even a 50/50 mix to help reduce the surface tension, which basically means it makes the water work a little better by allowing it to better stay in contact with the metal. It also provides some corrosion protection, but you won’t have any freezing protection if that’s an issue you need to be concerned with. I think it’s a good product with a purpose and it’s also readily available from many auto parts stores.

Engine Ice is a Propylene Glycol based mixture and I’ve never used it, but you can look at its specs to get a better idea of how it compares to the mixtures above. I’m sure it’s also a good product, but there are many good choices out there whether its Honda’s HP coolant, Yamaha’s coolant, Toyota’s coolant, Maxima’s coolant, Water Wetter, Evans NPG+, etc.

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