Coolant Replacement

Last time I rode, I went through some very steep, technical mountanous terrain. The coolant started bubbling. When I arrived home I noticed that the resevoir tank does not have any coolant left. I am assuming I should replace the coolant vs. filling? The manual outlines the replacement procedure and calls for the use of a radiator cap tester - is this really needed? Thanks for the help!

i'd replace it with some of the Engine Ice... i just bought some because i heard it works alot better than regular coolent and it better cause it costs alot more also...

i have been just adding water to mine though...

I wouldn't worry too much about the rad cap tester to start with, but i'd be looking into where your coolant is going, if it's overheating, excess from expansion should go to the reservoir out back, but since it's not and is actually disapparing FROM the reservoir, I'd be looking for an external leak or possibly internal (check your oil).

I ran about half the coolant out of mine in the last Hare Scramble i did - slow, muddy mess, on the gas all the time to go about 5 miles in an hour...I'd just add coolant to both the radiator and the resevior tank and watch it from there. Def check the oil and watch for leaks, too. Good luck!

Evans NPG-R, if you boil it out you have serious problems. its not cheap and involves running the old stuff out with a special flush. its available straight from Evans,just make sure its the R version;regular NPG is too thick:thumbsup:

I was also having problems with boiling over, but only during slow tight technical terrain where airflow through the radiators was limited. I was first running Maxima Coolanol and then switch to Engine Ice. It would still boil over after switching to Engine Ice. Currently I'm running Evans NPG+ and haven't had any boil over issues since. The Evans NPG+ does have a slightly higher viscosity than the Evans NPG-R, but it is a lifetime coolant that doesn't need to be changed. Evans recommends changing NPG-R every 2 years to maintain maximum corrosion protection. Zip Ty Racing also sells a coolant called XF+ Waterless Race Coolant in a 1/2 gallon bottle. I was told this is rebottled Evans NPG+. Evans sells a Prep Fluid that you can use to get all the left over water out of the engine after draining your prior coolant. Here's a breakdown between the different coolants I mentioned:

Engine Ice

50/50 propylene glycol & deionized water coolant

Boils 256°F

Freezes -27°F

Maxima Coolanol

50/50 ethylene glycol & deionized water coolant

Boils 265°F

Freezes -34°F

Evans NPG

100% inhibited propylene glycol

Boils 369°F @ 0psi

Freezes -79°F

Viscosity 2.8cp @ 212°F

Surface Tension 36dyn/cm

Evans NPG+

glycol blend waterless coolant

Boils 375°F @ 0 psi

Freezes -40°F

Viscosity 2.3cp @ 212°F

Surface Tension 44dyn/cm

Evans NPG-R

glycol blend waterless coolant

Boils 400°F @ 7psi

Freezes -10°F

Viscosity 2.0cp @ 212°F

Surface Tension 46dyn/cm

Great info Speedracer, thanks.

the R is primarily ethylene glycol which transfers heat a little better than the propylene glycol which the regular npg and the + are made from.

i'm guessing that zip-ty's choice to use the propylene glycol version is more for eco reasons than for its ability to perform better.

ethylene glycol is the stuff that kills critters,but if your careful it performs better for our application:thumbsup:

if your boiling regular coolant then something like evans is just a band aid. You should definately check the radiator cap for proper pressure, and those telling you not are giving you very bad advice. Pressure dramatically raises the boiling point and if you cant build pressure, its going to boil out.

How do you check the cap pressure - in the manual it references the use of a radiator cap tester and in the special tools section it lists part numbers for the tools. Are these Yamaha tools? Just trying to determine if I should try this by myself and buy the pressure test tools or take it to the dealership.

Thanks for the help!

After some further reading on similar posts - it seems like a good plan would be to replace the coolant with the Evans NPG+ and see how things go. If the problem occurs again a next step would be to replace the cap (vs. buying a tester which is expensive), if the problem persists - take it into the shop and let a pro take a look. The problem occured when I was riding very slow - very step inclines and declines so it was a perfect situation for overheating. Make sense? thanks for the help

How do you check the cap pressure - in the manual it references the use of a radiator cap tester and in the special tools section it lists part numbers for the tools. Are these Yamaha tools? Just trying to determine if I should try this by myself and buy the pressure test tools or take it to the dealership.

Thanks for the help!

The same pressure tester used to check for coolant leaks will have an adaptor to check the cap...mine was around 120 bills, you could just replace it..but a gamble as to the new one being good. If you buy genuine factory though you'll probly be fine

Before you make the switch to Evans waterless coolant make sure your jetting is correct. You don't want to mask lean jetting with a higher boiling point coolant. I'm running a JD jetting kit and really like it. Made the bike run much better and easier to start.

I pressure tested my cooling system and also replaced the radiator cap with a new stock Yamaha 1.1 bar (16lb) cap. This still didn't fix my overheating problem. I even tried running a Kawasaki 1.6 bar (23lb) cap to raise the boiling point of the 50/50 glycol & water coolant with no luck either.

My bike would run fine with no overheating issues during normal conditions like fast single track, fire roads, or open desert terrain. The problem occurs when your riding very technical slow rocky single track where your using the clutch a lot, stalling the bike, having to restart the bike, and reving the motor to get started again. You have very little airflow through the radiators. This combined with hot weather was causing my 50/50 glycol & water coolant to boil. You could run a fan like they have for the KTM's, but there's no room on my bike to install one.

The good thing about Evan's waterless coolant is that it does not build very much pressure in the cooling system. This will make it easier on your gaskets, seals, and hoses. Evans recommends using a 7lb cap with the NPG+. I called Evans and was told running the stock 16lb cap would also be fine since I couldn't find a lower pressure cap to fit the Yamaha radiators. Another good point about Evans waterless coolant is that it's non corrosive since it doesn't contain any water.

One disadvantage about using a waterless coolant is that it won't transfer heat as well and your bike might run 5 degrees hotter all the time. This really isn't a big deal considering it won't boil over like conventional 50/50 coolant. The problem with 50/50 coolant is that once it starts to boil you now have a vapor blanket against the hottest parts of the cylinder head instead of coolant. Since Evans won't boil it always stays in contact with the cylinder head and it's able to transfer the heat to the radiators.

Some people are afraid that by running a higher boiling point coolant they will not have any warning in case they have a major mechanical engine problem. If your engine gets that hot you should get some detonation letting you know you have a problem. I just ordered a Trail Tech Vapor computer for my bike so I'll be able to monitor coolant temps for peace of mind.

If you think that you might have some build up or scale in your cooling system you might want to flush it before switching to Evans. Just mix 50/50 distilled water & white distilled vinegar and run the bike till it's warm. Drain that and then refill with just distilled water. Run the bike and then drain again. If you have an air compressor you could try and blow as much remaining water out of the cooling system at this point . Your now ready to fill the bike with the Evans prep fluid to remove any remaining water. Run the bike a little and drain and then refill with which ever Evans waterless coolant you decide on.

Switching to a waterless coolant with a higher boiling point may not be the best choice depending on your riding situation. I ride in extreme conditions sometimes and have been running it for the last 3 years with very good results.

Thanks for the great feedback - much appreciated!!!

How do you check the cap pressure - in the manual it references the use of a radiator cap tester and in the special tools section it lists part numbers for the tools. Are these Yamaha tools? Just trying to determine if I should try this by myself and buy the pressure test tools or take it to the dealership.

Thanks for the help!

Sounds like something that I would try and avoid doing. Fill it up and Flogg it.

Can i use plain old 50/50 antifreeze such as wal mart brand, prestone, peak, etc? Thanks

Sorry i just realized this was in a yamaha section, I have a kawasaki kdx 220 if it makes a difference

I use motorcraft gold extended life coolant, but standard green should work too

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