01 426 WR overheating

Maybe I am being picky, but my WR seems to be overheating too much for my liking.

I know it is a big bike and it needs to be opened up to let the water flow. However, I like to take tight technical trails and that means a lot of first gear and idling.

My bike seems to really overheat fast when it idles. I spent the last 7 days with my sons camping and riding. We went up to some remote mountain lakes. I don't like my bike overheating so far up in the back country, especially when I have 2 boys with me.

Any ideas how I can fix this? Thanks! :)

....oops meant to put this in WR section....but you are welcome to respond here.

Overheating from idling is common to all 4 strokes, not just the WR.

Bottom line is if you stop for more than 20-30 seconds, turn it off, don't let it idle, especially of you have just been riding at slow speeds.

I rise in the desert all year round and often at slow speed. I have learned from experience to turn the engine off every time I stop regardless.

well what i did immediately for my bike was i purchased over sized radiators, and they fit just great. I just took my bike up for the first time last week after the rebuild

http://www.thumpertalk.com/forum/showthread.php?t=1000565&highlight=

and i was doing mostly 1st and second gear and a little bit of idleing but i rode technical single track and it didnt overhead at all.

if you look at my build the radiators have 30% more capacity than the stock ones and they were only like $100 on ebay.

One issue the OP faces is that he is riding at considerable elevation. The boiling temp is lower as elevation increases. The bike will boil over a lot sooner than if he were at lower elevations.

So, to repeat other posts, shut it down. Maybe look into engine ice or water wetter.

Hey slut... nice to see you running around over here (RMKcowboy from BCR).

In over 10 years of owning Yamaha thumpers I've only ever boiled on once, and that was following a little guy down the trail at very low speeds. I'd start with some fresh coolant and make sure its circulating properly. That bike of yours should have no issues with overheating unless the rads are plugged up or something.

The Radiator cap is the pressure regulator of the system. if the cap cannot hold back the required 16PSI then the coolant will boil at a much lower temperature.

The 426 already has huge radiators (larger than the YZ of that year) so as long as all the components of your cooling system are in good shape the 426 should be one of the last bikes on the ride to overheat.

The stock radiator in your build thread looked nasty. So replacement for you must have made good sense.

Fresh coolant and a new radiator cap every year will keep you nice and cool.

Fresh coolant and a new radiator cap every year will keep you nice and cool.

+1 on the cap. Many people forget about the radiator cap. I'm running a 1.6 bar tusk in my YZ450F and while it doesn't run cooler it does keep it from boiling over as quick. Maybe try a new cap or even a higher pressure cap. It won't make you cooler, but it will keep more coolant inside the bike for longer periods.

Overheating from idling is common to all 4 strokes, not just the WR.

Bottom line is if you stop for more than 20-30 seconds, turn it off, don't let it idle, especially of you have just been riding at slow speeds.

I rise in the desert all year round and often at slow speed. I have learned from experience to turn the engine off every time I stop regardless.

Ya I started doing that on the last ride.....thanks....good advice.

well what i did immediately for my bike was i purchased over sized radiators, and they fit just great. I just took my bike up for the first time last week after the rebuild

http://www.thumpertalk.com/forum/showthread.php?t=1000565&highlight=

and i was doing mostly 1st and second gear and a little bit of idleing but i rode technical single track and it didnt overhead at all.

if you look at my build the radiators have 30% more capacity than the stock ones and they were only like $100 on ebay.

So should I get an over sized radiator since the WR's radiator is already bigger than the YZ's?

One issue the OP faces is that he is riding at considerable elevation. The boiling temp is lower as elevation increases. The bike will boil over a lot sooner than if he were at lower elevations.

So, to repeat other posts, shut it down. Maybe look into engine ice or water wetter.

Yes I was at pretty high elevation....was riding at 7000 to 9000 feet when this happened. I forgot that fact about boiling points at higher elevation.

Hey slut... nice to see you running around over here (RMKcowboy from BCR).

In over 10 years of owning Yamaha thumpers I've only ever boiled on once, and that was following a little guy down the trail at very low speeds. I'd start with some fresh coolant and make sure its circulating properly. That bike of yours should have no issues with overheating unless the rads are plugged up or something.

Hey cowboy! :) Ya I know part of the issue is waiting for my son to catch up or going slow enough for him. That is why I was idling so much....but then on the next ride I started shutting it off while I waited for him.

Thanks for the advice on the cap RSanders and GCannon. I will definitely start there and put fresh coolant in. I had to use mtn stream water to fill up the coolant a lost...so I need to change it anyway.

Does it have a thermostat? What about yanking that out if it does?

well when looking at OEM parts between the 2001 yz426 and wr426 they have the same part number for both radiators, so they are the same size for both models. its just a suggestion to get the bigger capacity radiators but i haven't had any overheating problems, but i never ran it without the larger radiators.

and im ridding at 7000-10000 for most of my ridding.

well when looking at OEM parts between the 2001 yz426 and wr426 they have the same part number for both radiators, so they are the same size for both models. its just a suggestion to get the bigger capacity radiators but i haven't had any overheating problems, but i never ran it without the larger radiators.

and im ridding at 7000-10000 for most of my ridding.

ok thanks....i will look into the bigger radiator....what about the boyesen high flow water pumps?

you ride that high and you live in Delaware? what the? lol I am confused.

The only thing that worked for me was a fan, for riding behind a young rider I mean young riders. Tried rads, boysen pump helped but not enough to my liking.

The only thing that worked for me was a fan, for riding behind a young rider I mean young riders. Tried rads, boysen pump helped but not enough to my liking.

thanks kingquad

....btw peeps...my radiator is immaculate...it has a Devol guard over it.

ok thanks....i will look into the bigger radiator....what about the boyesen high flow water pumps?

you ride that high and you live in Delaware? what the? lol I am confused.

ya sorry i changed it, i currently live in Colorado... HA im not BS-ing you. i just have the stock water pump and it has worked just fine for me. If you have the money I'm sure it wouldn't hurt, but i would keep your stock one just in case you ever have to put that one back on.

the only small problem i ran into for the oversized radiators is that the rubber hose that goes through the frame from the left radiator to the right radiator is a larger diameter for the new radiators, i just clamped it down tighter with no leaking and when that hose ends up going bad i will replace it with some automotive radiator or oil line hose thats the right size.

DSCN7268.jpg

This might sound odd but radiator guards will help. I noticed my 426 running cooler after installing a set of unabiker’s. They act like a heat sink and carry some of the heat away from the radiator to be dissipated.

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