Gas leaking out the air intake

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mbrooks360

New Member
Aug 26, 2013
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0
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newark ohio
Turn the gas on, wait a few seconds it starts pouring out the air box. Is that a common problem? - or is the extension piece I welded on not allowing the gas to flow into the motor because it's pointing down hill towards the air box?


I'm thinking since it's not pointing where gas would flow into the engine that it's backing up in the carb and then going out the air intake. But then I'm thinking that even if that was the case would on a normal install eventually the motor would fill with gas, back up into the carb and go out the intake.

I moved the clip on the needle up. Other than that haven't down anything internally.
 

MotorBicycleRacing

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Jul 28, 2010
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SoCal Baby!!!
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Turn the gas on, wait a few seconds it starts pouring out the air box. Is that a common problem? - or is the extension piece I welded on not allowing the gas to flow into the motor because it's pointing down hill towards the air box?


I'm thinking since it's not pointing where gas would flow into the engine that it's backing up in the carb and then going out the air intake. But then I'm thinking that even if that was the case would on a normal install eventually the motor would fill with gas, back up into the carb and go out the intake.

I moved the clip on the needle up. Other than that haven't down anything internally.
Your fuel bowl is over flowing because there is junk under the needle valve
that shuts off the gas flow into the bowl or the white plastic float is full of gas.

remove the 2 screws and take the bowl off, then shake the float to see if there is
any gas in it.
Then remove the pin that the arms lever from to remove the needle.
Blow the the passage and seat out with compressed air.

Do not scratch or damage the brass seat that the needle valve seals against.

Liquid gas does not flow into the motor down the intake tube.
Gas is sucked up through the jet past the needle and atomized being mixed
with air as it flows down the intake tube.

I also notice that you are using both springs behind the clutch arm.
The big spring is only a heat shield fot the clutch cable so it doesn't
touch the hot cylinder head.
The small spring should be removed too as the internal spring is more than
enough to return the arm.
You are making the clutch pull at the bars harder than it needs to be.
 
Last edited:

BigBlue

Member
Nov 29, 2011
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California
Ditto ever thing MBR stated.

Is your fuel filter that close to the cylinder head or it just looks that way? I would move it if it is really close potential fire hazard or melting the filter.

Chris
AKA: BigBlue
 

2door

Moderator
Staff member
Sep 15, 2008
16,302
175
63
Littleton, Colorado
Ditto on both counts. The float valve isn't shutting off the flow of fuel from the tank when the bowl is full. Either the float is defective or there is dirt in the needle and seat of the float valve. I suspect dirt in the valve seat.

The kit fuel tanks should be cleaned and flushed prior to installation. They usually always contain rust and dirt. An in-line fuel filer is highly recommended but they can clog if the tank isn't cleaned.

Tom
 

crassius

Well-Known Member
Sep 30, 2012
4,032
158
63
USA
got no Xed out square in my browser - also got no access to docs.google.com src I see in the source code of his post
 

mbrooks360

New Member
Aug 26, 2013
8
0
0
newark ohio
Ditto ever thing MBR stated.

Is your fuel filter that close to the cylinder head or it just looks that way? I would move it if it is really close potential fire hazard or melting the filter.

Chris
AKA: BigBlue
has one actually caught fire or melted the filter? actually wondering.
 

mbrooks360

New Member
Aug 26, 2013
8
0
0
newark ohio
Your fuel bowl is over flowing because there is junk under the needle valve
that shuts off the gas flow into the bowl or the white plastic float is full of gas.

remove the 2 screws and take the bowl off, then shake the float to see if there is
any gas in it.
Then remove the pin that the arms lever from to remove the needle.
Blow the the passage and seat out with compressed air.

Do not scratch or damage the brass seat that the needle valve seals against.

Liquid gas does not flow into the motor down the intake tube.
Gas is sucked up through the jet past the needle and atomized being mixed
with air as it flows down the intake tube.

I also notice that you are using both springs behind the clutch arm.
The big spring is only a heat shield fot the clutch cable so it doesn't
touch the hot cylinder head.
The small spring should be removed too as the internal spring is more than
enough to return the arm.
You are making the clutch pull at the bars harder than it needs to be.
From what you described I think I damaged something one of the times I was putting the needle in.

I have a spare one to put on it for now and then I'll take apart the old one so I understand it better.
 

MotorBicycleRacing

Well-Known Member
Jul 28, 2010
5,844
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SoCal Baby!!!
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From what you described I think I damaged something one of the times I was putting the needle in.

I have a spare one to put on it for now and then I'll take apart the old one so I understand it better.
There are two "needles" in the NT carb.

The one you moved the clip on and the needle valve that is accessed
by removing the float bowl and float arm.
The needle valve I am talking about shuts off the flow of fuel into the
carb bowl by pressing against a brass seat which is part of where the
fuel line attaches to the NT carb.
 

mbrooks360

New Member
Aug 26, 2013
8
0
0
newark ohio
There are two "needles" in the NT carb.

The one you moved the clip on and the needle valve that is accessed
by removing the float bowl and float arm.
The needle valve I am talking about shuts off the flow of fuel into the
carb bowl by pressing against a brass seat which is part of where the
fuel line attaches to the NT carb.
Took apart the carb and the float was filled with gas.

Did notice the filter looked like **** and on an older one I built the line had hardened. Going to maybe start putting on metal inline filters and Thermo Tubing over fuel hose for cars.
 

2door

Moderator
Staff member
Sep 15, 2008
16,302
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63
Littleton, Colorado
Cracked and leaking floats are not uncommon and have probably been responsible for a lot of problems like yours.
Thanks for letting us know what you found. We really appreciate hearing what the problem was and if the advice you recieved helped.

Tom
 

crassius

Well-Known Member
Sep 30, 2012
4,032
158
63
USA
if you drop the float into a pan of boiling water, all will come out. Finding something to coat it with to seal it up again is hard though with all the diff types of gas around.
 

2door

Moderator
Staff member
Sep 15, 2008
16,302
175
63
Littleton, Colorado
if you drop the float into a pan of boiling water, all will come out. Finding something to coat it with to seal it up again is hard though with all the diff types of gas around.
Crass,
Is that really a good idea? Gasoline fumes and a source of heat like a gas ring on a range or even an electric eye? Sounds iffy to me. I would also think that any coating would effect the weight/buoyancy of one of those little plastic donuts. Just my thoughts.
My vote would go to replacing the float.

Tom
 
Last edited:

crassius

Well-Known Member
Sep 30, 2012
4,032
158
63
USA
do it all the time - takes a while, so I'd guess fumes are pretty sparse

I think the first time I did it was about 56 years ago & still got my eyebrows.