Overheating

So I went riding at glamis today and I had a little trouble with it overheating. It was a nice day, not hot, probably mid 80s at the hottest. I was running an 8 paddle tire and the bike is bone stock except for lowered gearring. I know this is a tough job for the little guy, but it did alright until I got on the sand highway heading north.

I had about a 15 mph tailwind, and it started overheating on me. Every time the red temp light came on I stopped, pointed it into the wind and let it idle. It would quickly cool down and the light go out. I'd give it a couple minutes to cool down then give it another run. It did this several times, I tried going fast 50-60 indicated on the speedo, slow about 30, and medium about 40. It lasted about the same time no matter the speed (which was about 2 minutes). Once we got out of the tailwind we played around on the dunes some more and it did alright until I would run it through multiple dunes consecutively really working it my Temp light would come on again. Once we started heading back south with the headwind I had no problems.

We got back, had lunch, and rode south with a headwind into the dunes, no issues until I really started working back in the dunes, back and forth in and out of the wind. It started overheating again, so I headed back, tail wind again, same cycle of overheating.

I think the combination of paddle tire in sand, and the tailwind was just more than it could handle. It just surprised me that the cooling system couldn't keep up on a nice day even with the tail wind. Anyone else experienced this? Any suggestions to prevent it other than just stay out of the dunes?

Well i suppose as i recently just gave advice on another thread where the very basic's had been over-looked - i will now cover all the bases & ask you here......

Is the coolant level with-in the normal range & at correct concentration mix etc ? - Also is the electric cooling fan operating all ok at those times when it was in the very hot range ?

Cheers.

There have been reports of the same thing (temp light coming on) while riding down the highway with heavy throttle.
I haven't read of any melt-down because it it, but the owners were concerned enough to write about it.

Assuming the above mentioned stuff (and everything else with the bike) is sound, I'd do what I did to my WR-250R and WR-250X:

1) Add a fuel programmer.
This will have the bike running cooler simply because it will no longer be so lean on fuel, and when you're riding off-road in sand for miles on end, you're opening the throttle asking for fuel (and air).
This is something practically any dual-purpose bike needs (richer fueling in the proper proportions) straight off the showroom floor (but your salesman won't tell you, probably because he doesn't know any better) if it's heading for some severe off-road use, whether the bike be carbed or FI.

2) Remove the black plastic duct on the rear side of the radiator.
I'd expect that while riding terrain known to the locals as the "sand highway", you won't want or need and little plastic ductwork restricting airflow through the radiator (which is there to duct hot air away from your leg while cruising down the street).

Once I did the fuel programmer and removed the duct, I never as much as heard the fan come on ever again, where before it would come on anytime it was warm weather with slow trail riding.
The bike ran noticably cooler and seemed happier.

I have to imagine there couldn't be a more torturous existence for a poor little ole wr250 than a paddle tire, in sand, with warm-hot temps.

What exactly are you running in your radiator?

It's still the factory coolant. The bike has about 3600 miles. Coolant level is good, and the fan definitely works. I've ridden it pretty hard on hotter days without issue, but never sand with a paddle. I think I'll try removing the shroud on the back, and change the coolant. Should I use like "engine ice", or just normal water/antifreeze mix? If its still a problem I'll look into the fuel programmer.

Does anyone know at what temp the overheat light comes on, and what it's normal temp range is?

according to this https://wr250rforum.forumotion.com/t8101-radiator-temperature

temp light goes on at 109C.

also keep in mind that ideally pure (distilled) water works best for cooling as it has the highest specific heat capacity (pure water on it's own isn't too good for the engine, but fine in combination with something like Water Wetter.) I've read a lot about this combo and how well it works, but never tried it myself. also not too sure how good it is with low temperatures. Where I am at, I need coolant that can keep up with temps below freezing, but if you're in a hot place where there is no risk of that, I'd give the distilled water + water wetter a shot (or at least do some research about it )

Thanks, I'll try a few of these suggestions. I'll post an update once I can get it out again (probably be a few weeks).

*update* and it doesn't look good. I think I confirmed my overheating problem So.....after cleaning the bike and doing all the post sand riding stuff I was down to the last thing, clean my air filter then go for a ride the next day.

When I opened my air box I was horrified, the box had at least 2" of sand in it. The filter was,literally holding the sand back, and it was completely caked in sand. The sand apparently absorbed all the oil in my filter and started blowing through. I got a significant amount of sand intrusion. Just being optimistic, I pulled the entire air box to clean it and I had sand all the way through the throttle body, (and I'm sure through the engine). Anyway I reassembled, tried to start her and nothing, just cranks over and not even a sputter. I dropped it off with a local mechanic who's checking it out (more just to confirm the inevitable).

I called around and apparently this engine wasn't really meant to be rebuilt. Most likely the cylinder, piston, valves and head all will need replaced. I'm being quoted in the $1200 (if piston and cylinder are good) to up around $3000 for a rebuild I could and would pay for the lower end, but I just don't know if its worth anything paying over 2k and judging by how much sand got through I think the whole things toast. I saw engines on eBay for $1800. But add labor to install it, and its still a questionable used engine. I'm seriously considering just selling it, is it worth much anything as is, or would I have to put in the money to get her running to get anything for her?

Wow, almost makes me sick just thinking about it, one day of riding, several thousand out of pocket. Lesson learned, rent somebody else's bike for the dunes!

Mmmmm.....Not good to say the very least mate.

If it is in fact that bad inside your engine then it may work out to be the cheapest option to just go for the complete Athena kit - either cheapest option as a standard bore, or if you do really want to keep the bike, then maybe the 290 B/B kit. They are under $700 for the complete cylinder, piston / ring, and full gasket kit, so maybe you just source & supply those parts to the Mechanic, and then you just have the labour, oils / filters & consumables cost. This could save you at least a grand straight up mate.

Check ebay for listings under "wr250r athena".


Cheers & good luck buddy.