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norm02

Boiling fuel or coolant?

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Hey all,

I've got a 2011 WR 450 that I bought new back in Feb. I've put 260 miles on it and I'll that I have done to it is taken out the pea shooter and so far that's it. I know, I know it's a whole nother animal once the other mods have been done. I light of that, my FMF 4.1 will be here tomorrow and then it goes to the dealership for its valve etc check, AIS and re-jet.

I rode it harder today then I have ever before on some pretty technical trails (a lot of 1st & 2nd gear hill climbs in heavy woods) and when I stopped to take a break I heard something boilng. It was coming from the front but sounded lit it was coming from above and behind the radiators. Looked at coolant tank under rear fender and nothing was bubbling and it didn't smell like it was hot.

Waited a while for whatever it was to cool down and I opened the gas cap to check on fuel level and as soon as I took the cap off it hissed for a second. I'm assuming since the location of the boiling sound was above and behind radiators ( right where gas tank is) that it must have been the fuel that boiled. I was running Chevron 93 octane.

Please let me know what you think and what i can do about it.

Thank you,

Jay

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It wasn't your fuel. It was your radiators boiling over. Just let the bike cool down for a while and ride again, you'll be fine. Mine boils too when I ride it hard.

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Its the nature of the beast.

Mine does the same thing after a lot of tight 1-2nd gear stuff.....but thats

why there is a resivoir....... when it boils over it goes to the tank and then

gets sucked back into the rads on cool down.

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It could easily be the fuel. Lots of us TT members have had this happen to us. First & foremost, remove the small "one way" valve in the gas cap breather hose. As you experienced, this one way valve won't allow the tank pressure to exit when the fuel starts to expand from heat. And since that pressure has to go somewhere, if it can't escape out thru the gas cap hose, it will instead pressurize the tank and force additional fuel into the carb causing "flooding" issues with your jetting.

And you can also insulate the underside of the gas tank to help to minimize the speed at which the tank starts to heat up. This will help some, as will getting the proper jetting in the machine, which will help to make the engine run cooler.

But the single most important thing is to remove that one way valve, before it starts "flooding" out your engine.

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Ok, thank you for the replies. Hopefully the re-jetting will help and I will take care of the breather as well. I'm planning on switching to either VP 110 or T4 so it will be interesting to see if that changes anything. If the coolant is boiling does it hurt anything and what can be done to minimize it?

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Why would you run such high octane fuel on a bike that's not even uncorked? Not understanding this....

Rejetting will definitely help the bike running so hot, so will uncorking it.

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well first off you need to get the bike to run right. you have had it way too long to have any excuse to not fix everything. uncork everything, exhaust , rejet it, adjust the valves, retard the cam. Then it won't overheat.

I run mine all year and I only was able to boil the radiators on one ride.. and that was from idling a nasty trail that had loads of dead fall in the heat of summer.

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As I mentioned in my initial post, it is getting "uncorked" this week. I am going to have the dealer do the AIS removal, throttle stop and re-jet it for the new pipe and higher octane fuel. Hopefully this will help it run cooler as you say and then I won't have any more issues. Thanks again for the help!

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I have this problem with the winter blend of 93 octane around here. After a hard ride you can put the end of the gas cap breather hose up to your ear and hear it bubbling.

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I know one guy who flooded his carb and blew hot fuel all over himself from his one way valve on his gas tank vent.. fuel boiled.

Also, retard your exhaust cam a tooth

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I know one guy who flooded his carb and blew hot fuel all over himself from his one way valve on his gas tank vent.. fuel boiled.

Also, retard your exhaust cam a tooth

My buddy had this happen to him on his first ride out on his 11' WR. Removed the one way valve and all was fine. If you are getting built up pressure when removing the gas cap this is most likely your problem.

You may also get fuel running out your fuel drain hose from the carb when this occures do to the pressure and the fuel needing somewhere to go.

Edited by mikewrf18

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I run 95 oktane as this is the fuel we get here with no problems , for boiling issues use Engine Ice in the rads and stop abusing the clutch in tech terrain - this causes massive heat buildup in the oil and heats the engine. Learn to ride in a flowing manner and your boiling issues will be at an end - works for me anyway.

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And you can also insulate the underside of the gas tank to help to minimize the speed at which the tank starts to heat up. This will help some, as will getting the proper jetting in the machine, which will help to make the engine run cooler.

My old '04 does this on the hot and heavy rides...although it doesn't seem to affect the way it runs or idles and I have never lost a drop of coolant.

What material would you use to insulate the tank bottom. Something like a metallic reflective tape...like the stuff for sealing ductwork? Or would the "metallic" nature of the tape just make things worse.

I wouldn't think that any thick foam type product would have enough room or survive very long under there.

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I've used the multi-pronged approach myself, including the metallic reflective tape. And the single biggest improvement was the removal of the gas cap vent check valve. Heck, I even drilled the vent hole on the gas cap larger, so as to never have the issue again. I think your right about not having enough room for any kind of thick foam type of insulation on the underside of the tank.

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My 09 has never over heated first thing after coming home my Boddy and I did all of the minimal mods and has ran like a champ last week end coolant boiled over wile wating to cross the Tecate border turned it off and walked to show passaport after that started and home I went.

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