Petcock leaking?

[Cra1g]

So I started the bike up after a few weeks of not riding it and discovered fuel dripping down the fuel hose at a pretty nice pace.

Turned the bike off and the petcock off, and it looks like the source of the leak is coming from the lower part of the diaphragm, pictured below:



It looks like there's a rubber gasket there, which might be the cause? Anyone ever experience fuel leaking from the petcock like this?

I didn't do any experimenting after discovering the leak -- I noticed it and then turned the bike and petcock off right away, and now here we are..

[asellus]

Looks like a good candidate for a rebuild.

While you wait for someone with actual experience with this problem, my gut reaction would be to loosen and tighten the clamping screws on that seal to cause it to reseat. That might buy you some time before needing to rebuild it.

Have a little read here if you haven't yet:
http://faq.ninja250.org/wiki/Rebuild...tcock/fuel_tap

[Triple Jim]

Is it working otherwise? I agree that I'd try tightening the screws as a first step. I've had that happen a couple times over the years.

[asellus]

Loosen and then tighten, to clarify my above advice. Simply tightening them is unnecessarily risky. Your goal is to have the sealing surface shift slightly, not clamp it way super tighter.

[Cra1g]

Originally Posted by asellus

Loosen and then tighten, to clarify my above advice. Simply tightening them is unnecessarily risky. Your goal is to have the sealing surface shift slightly, not clamp it way super tighter.

Thanks for the clarification. Did this to all four screws on the diaphragm, but didn't fix it

[asellus]

Originally Posted by Cra1g

Thanks for the clarification. Did this to all four screws on the diaphragm, but didn't fix it

Major bummer. Looks like a rebuild is in your future.

[Cra1g]

Update!

I retightened the diaphragm screws a second time, and I also took off the fuel line, ran gas through the petcock, and there was no leak.

Since I have an aftermarket fuel filter attached to the fuel line, that could be the cause if it was clogged or something. Going to go ahead and replace the fuel line and the filter and try it again.

[Triple Jim]

I'm glad you got the petcock leak fixed, but a clogged filter wasn't the cause.

[asellus]

Huzzah! +1 on the filter not being the issue. The bike wouldn't run if it was clogged enough to cause a leak like that. Besides, there's very little pressure on that line.

[Cra1g]

Alright, another update. I installed a new fuel line without a fuel filter and it looks like the leak is back, but in several spots..

There are two distinct areas where it's seeping: where the fuel line meets the petcock (which is where the leak starts as far as I can tell), and there's also a little seepage from the diaphragm where the rubber gasket is, which comes a little after the fuel line connection leaks. You can see the wet areas where the leaks are in the pic below..

[Triple Jim]

The correct size fuel line and a tightened clamp are all you should need to keep the line from leaking. If everything else about the petcock works correctly, a very light smear of EZ Turn fuel resistant grease on the gasket surfaces will seal it. Of course you have to open it up to apply the stuff, and use very little, because since it's fuel resistant, a glob of it that gets into the fuel line will clog something up downstream.

It's good to lube the moving parts of the hand valve of the petcock with it too. A 5 oz. tube is a lifetime supply. One source:

http://www.aircraftspruce.com/catalo...ezturnlube.php

[Cra1g]

Originally Posted by Triple Jim

The correct size fuel line and a tightened clamp are all you should need to keep the line from leaking. If everything else about the petcock works correctly, a very light smear of EZ Turn fuel resistant grease on the gasket surfaces will seal it. Of course you have to open it up to apply the stuff, and use very little, because since it's fuel resistant, a glob of it that gets into the fuel line will clog something up downstream.

It's good to lube the moving parts of the hand valve of the petcock with it too. A 5 oz. tube is a lifetime supply. One source:

http://www.aircraftspruce.com/catalo...ezturnlube.php

What would be the correct size fuel line? I think the new one I got is 5/16".

And for what it's worth, the old fuel line was seeping at the connection too, but it didn't look like it was originating there--likely the fuel from the diaphragm leak was running down and making it look like the connection was leaking. Could be the same situation here, though ¯\_(ツ)_/¯

[Triple Jim]

Originally Posted by Cra1g

What would be the correct size fuel line? I think the new one I got is 5/16".

The correct size is the size that takes a little effort to push on over the barb. It should seal even before you put a clamp on it. I have not owned my 250 long enough to have memorized the actual size (sorry).

[Cra1g]

Originally Posted by Triple Jim

The correct size is the size that takes a little effort to push on over the barb. It should seal even before you put a clamp on it. I have not owned my 250 long enough to have memorized the actual size (sorry).

It fits pretty snug--definitely doesn't slide on too easily. The carb end is an even snugger fit. Hell, it's a pain in the ass to try and slide it off..

[Triple Jim]

Sounds like a good size.

[asellus]

I doubt it's leaking through that barbed fitting, I think you're correct with the idea that it's just leaking around from where it's coming out near the diaphragm.

FWIW, my OE hose will weep if I don't put the silly ring clip on. We're talking pressures in the 1psi range at best here. The worm gear clamp you have there will make even an oversized hose seal just fine.

Rebuilding the petcock is the next logical step here, IMO.