Carb leaking into Cylinder when bike sits ?????

22 replies to this topic
  • d_criss

Posted March 22, 2002 - 05:17 PM


BigLou, makes perfect sence when you put it that way. Sometimes I don't think things through. I do have a problem with my xt's petcock not turning all the way off. Havent any reason to believe the 426's doesn't completely turn off. Even so, your point about the needle valve is most obvious.....duh!

Thanks for setting me straight. That's what I love about this site!


Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • John_Lorenz

Posted March 23, 2002 - 06:04 AM


Big_Lou is right here
The Petcock may not be shutoff or shuttoff fully, also he is right on the carb if there is leaking form there or the float is stuck. The carb should over flow unless that hole is plugged then there is no place to go but were gravity sends it. Down the throat of the beast. I would do the following jus as a test.
1: Pull the fuel line off the carb and stick a catch bucket under it. (Dont Do this In a closed Garage Fumes Eh Ignite) Do this on the side of the hous out in the drive or back yard if you can.

Check this out to validate if there is any leakage / sepidge from the fuel tank, making it a petcock problem. Even if the petcock is at fault the Float should shut it off, this indicates that something in the crab is wrong aka float level, dirt in the float valve assemble so on.

You probably already have this but if you do not it is wise to place a filter inline on your fuel supply....

Best of luck

  • DethWshBkr

Posted March 23, 2002 - 07:42 AM


You know, that stupid fuel breather check-valve DOES trap alot of air in there...I think it's a stupid thing to have. It's VERY possible that it is pushing fuel out through the carb....
Those gas tanks just balloon up....I wouldn't doubt that at the very doesn't help any.
Mabey this is the fuel pump though!!! :)

Related Content



Dirt Bike   Make / Model Specific   Yamaha   YZ 400/426/450
  • Hot  30 replies

Chubby dad, looking at bikes , First trip to the orange/black forum ! by Slow_ride

Dirt Bike   Make / Model Specific   KTM   250-530 EXC/MXC/SXC/XC-W/XCR-W (4-Strokes)
  • Hot  28 replies

Megabomb Fitment by 288yz450

Dirt Bike   Make / Model Specific   Yamaha   YZ 400/426/450
  • 1 reply

Is it worth it? (Cam and High compression piston) by macgi77

Dirt Bike   Make / Model Specific   Honda   CRF 150/230 F/L
  • Hot  36 replies

Yamaha YZ450F 2017 by Chris.GVS

Yamaha YZ450F 2017
  • * * * * *
  • 1 review
  • Last review by Tommyk_55
  • On January 15, 2017

Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.