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XR400R - Gas flowing out carb overflow

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Left town for a week after riding for a day, and when I got home Friday late afternoon I was anxious to go for a ride.  Roll the bike out to driveway and turn on gas.  Gas starts freely flowing out the overflow.  Now I am stumped as to what started this issue.  Carb was clean and it had fresh gas in tank since I had just re-jetted , and I rode it just a week ago.  And I had inpected the fuel cock a few weeks ago too.

So, knowing the bowl is full, I figured if I start it and run it, maybe it would clear up and was a fluke.  Now while warming up a half a minute I turn the fuel back on.  Sure enough it just flows out the overflow.  Next I took out a brass hammer and an aluminum flat punch and gave the bowl a couple of stern taps.  No change.

When parked I always either run the gas out of the bowl or use the drain screw to drain for storage.

Suggestions?  Explanations of the cause?

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ok.  I will get on that tonight or tomorrow night and give it a good check up.  

Just so everyone can get a bit of a giggle on the irony.  My daughter has a 200 2-stroke blaster that did the same darn thing just two weeks ago after running perfectly and sitting a week.  I had the carb out and was going to get a rebuild for it this week and Friday my XR does the same thing.  :banghead:  This problem has never happened to me in 30 years of riding.  The odds of it happening 2 times in as many weeks IMO is ridiculously low

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Not to be smart but did you tighten the drain screw back up after the last ride?

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And have you bought a couple in-line filters? If not you need to, otherwise you will continue to get trash in the needle valve.

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When parked I always either run the gas out of the bowl or use the drain screw to drain for storage.

 

 

double post

Edited by Baja Rambler

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When parked I always either run the gas out of the bowl or use the drain screw to drain for storage.

 

 

When you do this, the rubber on the tip of the float needle dries out and cracks.  If you leave the ethanol gas in for more than a month, it gums up the carb.

 

I use fuel stabilizer and techron in the gas and only turn the fuel off when I transport the bike on a truck or trailer. 

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Just a suggestion my float stuck once I just took a soft rubber mallet and softly (I mean softly dang it!) Hit the carb bowl a few times. Just enough to wiggle it lose in there... I know its not the proper way but got me running until I did a carb rebuild over the weekend

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Even if the rubber on the float needle valve looks good, it can still be bad, just replace it.

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If both bikes did this I'd take a look at your fuel jug, see if you picked some bad gas. It really would be a shame to clean both carbs and dump some more crap back in the tank. The mallet mentioned above can work. And yes the ethanol is pure crap especially if you live in a region where it is oxygenated it turns to crap quick. I'm lucky there is a station near me sells racing fuel 7.00 a gallon worth it.ethanol contains water as it evaporates it leaves water behind slowy builds up in tank one drop will clog needle and you can't see it

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This has been discussed a few times.

Tapping with a wood handle and draining out gas a few times will work. I've done this while out riding,

If there is anything in the fuel, it can keep the float open.

I added a fuel filter to prevent this from happening again.

Cleaning the carb works.

Rebuilding works.

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We're definitely getting screwed with ethanol.  It's fine for a daily driver because it absorbs moisture and blends it with the fuel--no more rusty fuel tanks in you daily drivers.  The problem is when the bike or car sits and goes through heat cycles and evaporates in the carb.  This condenses the moisture along with some other gunk.  

 

The rubber compound on the float needle is not entirely impervious to the solvents in fuel.  Some aftermarket float needles may use an inferior rubber compound but even the best known compound is not entirely impervious to some solvents.   One case in point is when you install a brand new, soft, and supple Honda fuel hose.  Over time, the hose compound becomes hardened, especially if it sits on the shelf and dries out.  

 

One point of entry for dirt is the fuel line when disconnected at the tank.  A tiny speck of mud on the bottom of the tank, flicked into the end of the fuel line can be a disaster inside the carb.  Plug the fuel line as soon as you disconnect it.  

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