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fuel out vent tube in prime

  • Thread starter Thread starter cowb0y
  • Start date Start date
C

cowb0y

Guest
Fuel streams out the vent tube between carb one and two while petcock in "prime" and bike not running. When bike is running, petcock in "on", fuel leaks from same area once the bike warms up dumping fuel everywhere. I just pulled the carbs and set the floats per the manual (with gasket installed). I do have the vent tubes off and this problem just began two weeks ago on my daily commuter. Not sure whats goin on.
:confused:
 
Remove the needles and seats and inspect for wear. If worn, you'll need to replace them.
 
needle valves where inspected and found clean and minimal wear. Petcock stops the flow of fuel in the "on" position and bike runs normally except for this new leaking issue. Are there any tricks to testing the petcock?
Could the vent lines being off cause enough loss of negative pressure in the carbs to allow fuel to flow out only the vent line between carb 1 and 2?
 
If it is the petcock, would a rebuild kit be sufficient?
Click to expand...

Rebuild kits usually cost about half that of a new petcock and usually do not work(sometimes they do if you are lucky). Best bet is to spend the money on a new petcock and be done with it.

I just pulled the carbs and set the floats per the manual (with gasket installed).
Click to expand...

There may be your problem, not supposed to have gasket installed when measuring the float height. The measurement is taken from the gasket
mating surface (where gasket lies) not from the gasket surface. The fuel level in the bowl is too high that is why its overflowing.
 
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Ooops, my mistake. Gaskets were out when measured the float heights at 22.4 mm with just a light touch of the micrometer to the top edge of the float and the bottom of the tool resting on the flat space between the gasket ridge and the edge of the carb.

Still interested in testing the petcock before I go spending $50+ bucks. Any ideas??
 
Sounds like you pretty much got it figured out, glad you were able to get it fixed.
 
no, no, no. I still got the fuel dumping out the vent line, I just mistyped earlier.

I decided to try to run it for a minute and the fuel now POURS out just the one vent line worst than before. Maybe I need to set the floats higher, thus engaging the needle valves earlier? Say 23 or 24 mm?? But carb 3 and 4 are set at the factory height and are not leaking, this also makes me think the petcock is functioning.

Or since fuel comes in the carbs at #2 and the vent line between #1 & #2 is so close, this is the most likely place for fuel to flow out first. I mean it FLOWS. I got the side of the air box wet with fuel from the stream out the vent line while the bike was idling.

I dont feel like this is a float issue from the level of fuel flowing or I could be wrong, but then again #3 & #4 arent leaking so maybe not a petcock issue either.

However, since I took the carbs apart, inlcuding the needle valves, last night, set the float heights with the gasket OUT and the problem is worse this morning makes me thing I could increase the float height and fix the problem. Argghh!
 
The needle valve may have stuck open when you took them out. Try tapping on them with a screwdriver or something.

Does it flow out if the bike is off and the petcock is set to ON ? It shouldn't.

Basically, fuel will flow freely in the PRI position whether the bike running or not. The only thing ,at that point, to keep it from overflowing is the needle valve seats.

If you have fuel flowing in the PRI postion, you're supposed to. If it's overflowing, then you have issues with the needle valves.

If you have fuel flowing with the petcock in any other position with the bike NOT running, your petcock is done.
 
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Fuel overflowing when running is either the float lever or the float needle. Did you replace the float needle O ring?? With the engine off No fuel should flow from the petcock.. ON prime it flows all the time
 
There is no sense taking the time giving him advice, he already "knows" how to fix it. He set the float level correctly, the needle valves and seats are perfect. The petcock is working like it should. Let him fix his bike.


If it's overflowing, then you have issues with the needle valves.
Click to expand...

Not true Larry...you are wrong, his needle valves are perfect. There could NOT be any issues with those needle valves. Did
I mention they are perfect.
 
almarconi said:
There is no sense taking the time giving him advice, he already "knows" how to fix it. He set the float level correctly, the needle valves and seats are perfect. The petcock is working like it should. Let him fix his bike.




Not true Larry...you are wrong, his needle valves are perfect. There could NOT be any issues with those needle valves. Did
I mention they are perfect.
Click to expand...
and that is from the mouth of mr perfect!!!!
 
No perfection here, jus frustration with carbs. Thanks for the explanations. Sounds like I have to tear into them again. When I inspected the needle valves, there were no deep grooves on the needles and each sprang back when pushed, so I thought they functioned. I did not replace the O-rings tho.

I think I will try settin the floats 1mm higher and see what happens. Thanks again.
 
cowb0y said:
No perfection here, jus frustration with carbs. Thanks for the explanations. Sounds like I have to tear into them again. When I inspected the needle valves, there were no deep grooves on the needles and each sprang back when pushed, so I thought they functioned. I did not replace the O-rings tho.

I think I will try settin the floats 1mm higher and see what happens. Thanks again.
Click to expand...

Don't mess with the floats. Replace those o-rings. Get the kit from Robert Barr at Cycle O Rings Dot Com, and rebuild those puppies the right way. Even if they look ok, I guarantee you that those o-rings are trash at this point in time, if they're not been replaced. Imagine how you'd feel if you were dunked in gasoline for thirty some odd years. The problem gets worse each time you take them apart because those o-rings are tearing a little each time they get pulled. You might not be able to see the tears, but the fuel will find a way through.
 
Turtleface said:
Don't mess with the floats. Replace those o-rings. Get the kit from Robert Barr at Cycle O Rings Dot Com, and rebuild those puppies the right way. Even if they look ok, I guarantee you that those o-rings are trash at this point in time, if they're not been replaced. Imagine how you'd feel if you were dunked in gasoline for thirty some odd years. The problem gets worse each time you take them apart because those o-rings are tearing a little each time they get pulled. You might not be able to see the tears, but the fuel will find a way through.
Click to expand...
Ditto
O-rings
 
Larry D said:
The needle valve may have stuck open when you took them out. Try tapping on them with a screwdriver or something.

Does it flow out if the bike is off and the petcock is set to ON ? It shouldn't.

Basically, fuel will flow freely in the PRI position whether the bike running or not. The only thing ,at that point, to keep it from overflowing is the needle valve seats.

If you have fuel flowing in the PRI postion, you're supposed to. If it's overflowing, then you have issues with the needle valves.

If you have fuel flowing with the petcock in any other position with the bike NOT running, your petcock is done.
Click to expand...

:clap:



Turtleface said:
Don't mess with the floats. Replace those o-rings. Get the kit from Robert Barr at Cycle O Rings Dot Com, and rebuild those puppies the right way. Even if they look ok, I guarantee you that those o-rings are trash at this point in time, if they're not been replaced. Imagine how you'd feel if you were dunked in gasoline for thirty some odd years. The problem gets worse each time you take them apart because those o-rings are tearing a little each time they get pulled. You might not be able to see the tears, but the fuel will find a way through.
Click to expand...


:clap:
 
Petcock is OK. It flows on prime, and doesn't when off prime. Good or bad though, the float needles are supposed to stop the gas. Maybe it's some crap in them from a dirty tank or as said just replace them and the orings. Oh yeah, if it's got brass floats maybe one of them is full of fuel and sank or maybe the float is binding or sticking when you put the bowl back on. Shake the carb, you should hear the float rattle. It shouldn't be that difficult to figure out ........famous last words.:D
 
Floats rattle and are integral (empty of fuel). O-rings makes sense from my experience and troubleshooting on these carbs. Got the O-rings on the way and will cautiously replace each upon arrival. I truly appreciate understanding the "why" of what I am doing.
 
cowb0y said:
Floats rattle and are integral (empty of fuel). O-rings makes sense from my experience and troubleshooting on these carbs. Got the O-rings on the way and will cautiously replace each upon arrival. I truly appreciate understanding the "why" of what I am doing.
Click to expand...

When you're sliding them back in the seats with the new orings, put a little spit on 'em so they will slide in easily. Be careful not to nick them.:)
 
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