Help with a yz426f overheating

You guys are probally gonna kill me but excuss my newbiness in thumperville. I just accuired a yz426f and it runs great. I rode it today for about ten minutes. Took it down the road and then let it idle in the backyard for 2-3 minutes. At this point it began spitting coolant(blue ice) out of the overflow. Is this normal for this to happen? I have heard that you have to keep these bikes moving but this seems very weird. Is there anything that you can do to help this?(Fan or anything) I bought this for trail riding but am not sure it was a good choice if it cant idle without overheating. Help please very frustrated.

You let it idle for way to long. Always shut it off if your sitting still for more then 30 seconds or so.

wow how hot was it out? i can ride mine and sit idling for a couple minutes without any problems. just yesterday it was probably near 80 or above(it's 84 right now) and i went trail riding on our h/s practice loop(single track) and had to stop and clear limbs and what not more than a handful of times and most of the time i'd just hit neutral and let my buddy hold my bike while i moved the debris... no problems... i'm running engine ice also...

What cap do you have? I currently have the stock 1.1 on there and it will start spitting out the fluid after a pretty short period of time, 2min max. Going to pick up a 1.8 to combat the problem.

Riding in hot socal deserts.

mines the stock cap too. honestly it has yet to overheat on me... actually, this has me hoping there's not something wrong with my cooling system :thumbsup:

I just think that it is weird that you cant let it idle setting without it getting hot. Are there any solutions to this?

mines the stock cap too. honestly it has yet to overheat on me... actually, this has me hoping there's not something wrong with my cooling system :thumbsup:
It's probably empty.
I just think that it is weird that you cant let it idle setting without it getting hot. Are there any solutions to this?
Keep moving, idle facing into a 10 mph wind, or use a battery powered fan.
It's probably empty.

lol, my maintenance hasn't fallen to that level just yet bro. actually i just flushed and refilled my radiators yesterday to be exact. and always keep a careful eye on all my fluids. i just don't think it's gotten hot enough here yet for me to have really overheated it. just got the yammi end of last season and yesterday was the first really hot day we've had around here :thumbsup:

i think a few minutes is way too fast. i was out at the dunes this weekend on my 400 in 80+ heat and it never spews coolant while at idle, or any time for that matter. and its full of good clean coolant with a stock cap

In most reasonable weather, they'll idle for a minute or so without a problem. What I find out a lot of the time is that "I only let it idle for a couple of minutes" was really much longer than that. If you really think of how you ride, most of the time, you don't really let it sit there that long.

I have a 1.1 radiator cap on it. Do you think thats the prob.

No, I don't.

Is it possible that I could have a blown head gasket? What should I look for? The thing runs like a scalded dog lots of compression.


Is it possible that I could have a blown head gasket? What should I look for? The thing runs like a scalded dog lots of compression.


Check your oil to see if it is milky and keep an eye out on your radiator fluid level.

Chances are there is nothing wrong and as gray said your "couple of minutes" may have been more like 4-5 minutes which is too long to sit and idle.

I have the stock cap on mine and have let it sit for close to 2 minutes with no radiators fluid overflowing.

Also a small pilot jet may cause it to get a little warmer than usual but that is unlikely to be your problem.

mine does it all the time when I;m going really slow. Don't worry about it. It's normal. Thats why the WR has a recovery tank.

Oil in the resivoir is normal. I have talked to people that say that there 426 has never boiled over. How do I check that the water pump is working appropriatly?

Where is the thermostat?

There is no thermostat.

Gray I think you mentioned looking under the rad cap to check for bubbles. I didny see and definable bubbles but the is alot moving around down there. Check out my video and see what you think.

Can't tell anything from that.

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