Gas Out the Exhaust?

Moto

Moto

Member
I just built this bike for my friend and hes having some sort of weird flooding issue. When you park the bike everything seems fine, but within a few hours it will spill gasoline all over the floor. (quite a bit) Im pretty sure its coming out the exhaust, because when you go to start it after this problem happens has happened gas usually comes pouring out the pipe when the engine turns over. Once the engine has been de-flooded however it runs excellent with no problems. Any ideas on what is happening? Its an NT carb with the needle set 1 notch leaner than stock and an otherwise completely stock setup. Ive never had any problems like this with my other bikes.

77392264-8B16-49A9-B24C-77FBFE6E9CF8-6736-0000020FEB109B81_zpse66513f6.jpg


C879E171-071D-4CCA-8C31-BE07D8300859-6736-0000020FE4767D90_zpsf69b87fe.jpg
 
Are you turning off the fuel valve when the motor isn't running? That should control the issue. However, it seems likely that the root of the problem would be a float/needle valve issue. Either it is not closing all the way due to some debris stuck in there, or some manufacture defect, or the float is just set too high. Also, sometimes a float can leak and take on fuel (inside the float), if that happens you will get this problem. If your carb is tilted heavily it may cause this problem and it may be alleviated by adjusting the float so it holds less fuel in the bowl.....
 
nightcruiser said:
Are you turning off the fuel valve when the motor isn't running? That should control the issue. However, it seems likely that the root of the problem would be a float/needle valve issue. Either it is not closing all the way due to some debris stuck in there, or some manufacture defect, or the float is just set too high. Also, sometimes a float can leak and take on fuel (inside the float), if that happens you will get this problem. If your carb is tilted heavily it may cause this problem and it may be alleviated by adjusting the float so it holds less fuel in the bowl.....
Click to expand...

I have never needed to turn off the fuel valve in the past, but thats an easy fix. I did rebuild the carb earlier and checked / adjusted the float so that it is lower. I may just rebuild the carb with some other parts I have and see if that solves the problem. Carb is pretty straight. Ill go double check the float again (:
 
As Nightcruiser stated, it is probably the float needle valve or the float itself has a pin hole and is filling with gas. Seating surface for the float needle valve maybe worn or has a bunch of gunk to prevent proper seating.

That carburetor don't look level sitting in the bike frame. That was the first thing I noticed when I opened your post.

Float should be 21mm from gasket seating surface on a HT engine.

Good Luck,

Chris
AKA: BigBlue
 
I've seen a lot of bikes that will fill the engine with fuel if you leave the petcock on while it is leaning on the kickstand.
 
nightcruiser said:
Are you turning off the fuel valve when the motor isn't running? That should control the issue. However, it seems likely that the root of the problem would be a float/needle valve issue. Either it is not closing all the way due to some debris stuck in there, or some manufacture defect, or the float is just set too high. Also, sometimes a float can leak and take on fuel (inside the float), if that happens you will get this problem. If your carb is tilted heavily it may cause this problem and it may be alleviated by adjusting the float so it holds less fuel in the bowl.....
Click to expand...


This basically says it all. Recheck the float valve needle and seat. Might be a small nick in the tip of the needle since they are relativly soft. Since your leak seems to take awhile to occur, I'm guessing a damaged needle or seat.
 
you should always turn the fuel off. the weight of the fuel will easily overpower the float on a nt carb.

and if you leave your bike in the garage, a big puddle of fuel is a fire hazard.
 
Moto said:
I just built this bike for my friend and hes having some sort of weird flooding issue. When you park the bike everything seems fine, but within a few hours it will spill gasoline all over the floor. (quite a bit) Im pretty sure its coming out the exhaust, because when you go to start it after this problem happens has happened gas usually comes pouring out the pipe when the engine turns over. Once the engine has been de-flooded however it runs excellent with no problems. Any ideas on what is happening? Its an NT carb with the needle set 1 notch leaner than stock and an otherwise completely stock setup. Ive never had any problems like this with my other bikes.

77392264-8B16-49A9-B24C-77FBFE6E9CF8-6736-0000020FEB109B81_zpse66513f6.jpg


C879E171-071D-4CCA-8C31-BE07D8300859-6736-0000020FE4767D90_zpsf69b87fe.jpg
Click to expand...

the float is stuck:-||
 
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