WR250F dying in puddles

My '08 WR250F dies when going through deep puddles. You can start it in neutral or with the clutch pulled in and rev it to the high heavens, but a soon as you get moving it just dies, almost as if it instantly ran out of gas. It doesn't jolt as if the clutch was popped, it just stops. Once I walk it out of the puddle, it runs like nothing's even happened. It also runs fine in average depth puddles. Any thoughts on what this could be? I'd rather not have to make the walk of shame out of a puddle again

Probably because all of the carburetor vent hoses are routed down to the bottom of the frame and point at the ground when the bike rolls off the showroom floor.

When the carb vent openings are under water, the bike quits running.


This is solved by routing half of the vent hoses (one from each side of the carb) up and away from the water you're crossing.

Hmmm, wouldn't it be a good idea to route them all up then? Maybe keep crap from getting sucked up into the carb?

The vent hoses don't suck water up into the carb.

The hoses vent the carburetor body to atmospheric pressure.


The way I understand it, two go up high and two stay down low.

Then where did all the crud in my float bowl come from and why do they make filters for the vent hoses?

I think YZEtc is right.


What does the Crud look like?

VERY common problem.

Have a read of stickies. And search a bit more. Lots of good fixes and pictures.

This is from the James Dean Jetting FAQ:




I can see dust eventually getting into the float bowl, but not sucking up water from a water crossing.

Maybe if you completely submerged the bike, or pulled the choke and tried starting the bike with the vent hoses submerged - James Dean mentions the choke operation in that FAQ.


I believe the reason you leave two vents pointing downward is in case you do get a bit of gasoline (or water) in the vent line and allowing it a way to drain off.

I remember when the carburetor T-vents got popular on motocross bikes in the 1990s.

Edited by YZEtc

my yz does that also when going thru deep crossings. I had to keep her rev'd every time after the 1st crossing.

I think YZEtc is right.


What does the Crud look like?

Plain ole dirt!

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