help..


4 replies to this topic
  • TwentyThreeMX

Posted April 26, 2009 - 05:09 PM

#1

sry posted in general thread also but wanted to maximize my possibilities for a response!!


Hoping someone may have experienced this before or might have an idea...

I was riding my 06 yz450f on saturday. It seemed like it was stalling a little. I thought maybe it was me for some reason.. so i ignored it. Then it got kind of worse.

I just raced last week and noticed gas coming up a little bit from the cap around the vent tube. I have one of the short ones with the cap..

I got back off the track and put the bike on the stand and gas was pouring out of one of the tubes (assuming the overflow, dont know what all them tubes are down there). Soon as I loosened the gas cap it stopped... and you could hear it relieve all of the pressure in the tank.

I thought maybe the gas cap or that vent hose was screwed up.. so I took the cap off of my 06 yz250f and put it on there and it was stil doing same thing.

It got real bad I hit a pretty big jump and it just stalled out as soon as I let off the gas off the face of the jump. Thats when I put it in the truck for the rest of the day.

Its definitely building up pressure in the tank, but what could be doing that? I've always ran the same gas, I've had those caps on there since I got the bikes 2 years ago, and I live in Cleveland and its not even that hot out here yet..

Any ideas anyone? I looked at all the hoses, everything looks clear. I washed the bike before.. no mud or anything covering up any hoses. I'm clueless! Don't want to just start taking apart the carb if someone can point me to 1 speecific thing or something. The bike hasn't been apart or anything recently, other than oil changes and air filters.

  • ThumperKid250F

Posted April 26, 2009 - 05:15 PM

#2

sry posted in general thread also but wanted to maximize my possibilities for a response!!


Hoping someone may have experienced this before or might have an idea...

I was riding my 06 yz450f on saturday. It seemed like it was stalling a little. I thought maybe it was me for some reason.. so i ignored it. Then it got kind of worse.

I just raced last week and noticed gas coming up a little bit from the cap around the vent tube. I have one of the short ones with the cap..

I got back off the track and put the bike on the stand and gas was pouring out of one of the tubes (assuming the overflow, dont know what all them tubes are down there). Soon as I loosened the gas cap it stopped... and you could hear it relieve all of the pressure in the tank.

I thought maybe the gas cap or that vent hose was screwed up.. so I took the cap off of my 06 yz250f and put it on there and it was stil doing same thing.

It got real bad I hit a pretty big jump and it just stalled out as soon as I let off the gas off the face of the jump. Thats when I put it in the truck for the rest of the day.

Its definitely building up pressure in the tank, but what could be doing that? I've always ran the same gas, I've had those caps on there since I got the bikes 2 years ago, and I live in Cleveland and its not even that hot out here yet..

Any ideas anyone? I looked at all the hoses, everything looks clear. I washed the bike before.. no mud or anything covering up any hoses. I'm clueless! Don't want to just start taking apart the carb if someone can point me to 1 speecific thing or something. The bike hasn't been apart or anything recently, other than oil changes and air filters.



its that little shorty gas vent tube you got. go get the stock one and you should be fine

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  • Todddob

Posted April 26, 2009 - 05:40 PM

#3

I had the shorty on my yz250 last year and it was fine, this year on my 07 450 after a couple laps gas comes out of it???I like the shorty, maybe extra pressure in the 4 strokes?

  • TwentyThreeMX

Posted April 26, 2009 - 07:17 PM

#4

hm..i dont know. ive ran that shorty thing for like 2 years now.. but just to be sure it wasnt clogged or somehow screwed up, i switched caps from my 250f to the 450 and it was still doing it..

but my 250f is fine.

i think if that thing was a problem it would have done this a year or so ago?

  • grayracer513

Posted April 26, 2009 - 08:10 PM

#5

sry posted in general thread also but wanted to maximize my possibilities for a response!!

Cross-posting the same thing in more than one forum is actually a breach of the forum rules.

I would guess it's a problem with the batch of fuel you have. Has the gas been sitting a while? Does the station you buy from do a lot of business, so that their gas is usually fresh?

Fuel tank vents are generally set up allow air to flow in fairly freely, but to resist letting pressure out. They will allow air to escape, but not very rapidly. If there is something about the gasoline which causes it to release an unusually large amount of vapor when agitated, the pressure in the tank may rise to problematic levels. This would explain the flooding (fuel out the overflow), which would result when the pressure in the fuel tank was high enough to force the float needle off its seat.

I think I'd start with some fresh gas from an alternative source, and see what happens.





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