What is a duck bill valve and what is its purpose? Working on a Homelite super 240. With .325 .50 18". Got it running great now, but still seeps gas when just sitting not running leaving a puddle. Wonder if this duck bill valve has any thing to do with this. UT-10717 Anyone know years made, has magnesium case and sides. I think 39.3cc
What is a duck bill valve?
- Thread starter Cut4fun
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spacemule
The Peanut Gallery
If I'm not mistaken, a duckbill valve is a rubber valve with two rubbers flaps resembling a duck beak. It allows fluid to move one way through the valve, but not the other way, acting as a check valve. I wasn't aware they put them on saws.
Lawn Masters
Addicted to ArboristSite
McC used something to this effect on the Mac 110 series oilers. worked well I as I recall using one.
Mange
Addicted to ArboristSite
You describe it pretty well Mule, but it is usually metal flaps, they usually sit on the crankcase between it and the carb, to prevent back pressure.
That means there is no intake port on the cylinder, more flush ports instead in some saws.
I could be completely wrong though, the tek Eng still need a bit of polish
That means there is no intake port on the cylinder, more flush ports instead in some saws.
I could be completely wrong though, the tek Eng still need a bit of polish
formersawrep
ArboristSite Operative
Older Homelites definitely had them (XL-2, Super-2, etc) and they were famous for leaking as described. They are fairly small and all rubber.
Mange,what you are talking is reed valve.Mange said:You describe it pretty well Mule, but it is usually metal flaps, they usually sit on the crankcase between it and the carb, to prevent back pressure.
That means there is no intake port on the cylinder, more flush ports instead in some saws.
I could be completely wrong though, the tek Eng still need a bit of polish
Mange
Addicted to ArboristSite
Yep. I was wrong, thought that was just another name for it :umpkin:
I go lay down now!
I go lay down now!
Lawn Masters
Addicted to ArboristSite
Well, you'll get used to it sooner or later. these things confuse some of US even, so dont feel too bad.
Fish
Tree Freak
I had a girlfriend who's nickname was "Duckbill Val", she was ugly as sin, but she had talent.
ozflea
Good ol' BP Zoom 25-1
Well Fish we won't go there to many old memories, some great others no so.
Mc Bob.
Mc Bob.
Mike mandry
ArboristSite Guru
It is the fuel tank vent valve. It allows air in the tank, so a vaccum does not build up. Its a one way valve. Air can come in the tank, but not out.
They cost about $1.50
Some of the smaller Homelites (Xl, Xl2 etc...) etc used them in the oil tank, as part of the auto oiling system. Crankcase pressure was forced in the oil tank & the pressure fed the oil to the bar. If the valve was bad, pressure could not build up & it would not oil........
They cost about $1.50
Some of the smaller Homelites (Xl, Xl2 etc...) etc used them in the oil tank, as part of the auto oiling system. Crankcase pressure was forced in the oil tank & the pressure fed the oil to the bar. If the valve was bad, pressure could not build up & it would not oil........
NevadaWalrus
ArboristSite Operative
Mike has it right.
Acutally these valves are more common then you might expect. Pretty common on Echo products you just don't see them. Older Echo fuel caps have them, today on line and hedge trimmers Echo has a separate vent line going to a breather valve, inside the plastic body is a duck bill vent.
Acutally these valves are more common then you might expect. Pretty common on Echo products you just don't see them. Older Echo fuel caps have them, today on line and hedge trimmers Echo has a separate vent line going to a breather valve, inside the plastic body is a duck bill vent.
lesorubcheek
Addicted to ArboristSite
Mike's explanation is right on. I know the little XLs use a duckbill valve for pressurizing the oil tank, but it looks like from the IPLs that the 240 just uses 'em for vents instead of having vented gas and oil caps.
Back to your original problem of fuel leaking, does it leak even sitting level with the tank 1/2 full or less? About the only leak the duck bills would contribute to would be leaking directly from the tank when tilted. Some fuel will slosh around from vibration when running, but if its leaking while just sitting and not running, I'd guess you have a problem somewhere else to look for.
Good luck,
Dan
Back to your original problem of fuel leaking, does it leak even sitting level with the tank 1/2 full or less? About the only leak the duck bills would contribute to would be leaking directly from the tank when tilted. Some fuel will slosh around from vibration when running, but if its leaking while just sitting and not running, I'd guess you have a problem somewhere else to look for.
Good luck,
Dan
Those little duck bill valves were also used in the fuel caps of most of the big HOMELITE's under the scinitered bronze plug. Check your SXL, XL12's etc. When they age, the rubber turns to goo. The plug comes out with a little prying with a sharp icepick like tool.
Bill Walcott
Bill Walcott
GASoline71
Mr. Nice Guy
As a sidenote... Reed valves as explained earlier are usually used in high performance 2-strokes. Such as dirt-bikes , snowmobiles, etc. But maybe some saws had them too? Yes/no?
Gary
, snowmobiles, etc. But maybe some saws had them too? Yes/no?Gary
Lawn Masters
Addicted to ArboristSite
There were a few models without reed valves, the 350, 360, 450, 550, 650, 750, to name a few.
Somebody suggested to loosen the gas cap before storage. I tried this after making some test cuts with the newly sharpened stihl .325 .50 RM chain. Checked it today and not one leak from the gas mix anywhere. I did go one step further and loosened the gas and oil caps, just in case. Thanks for the idea, to whoever brought that up.
ozflea
Good ol' BP Zoom 25-1
Duck bill valves were also used in McCulloch saws
1. Inside the fuel cap as a pressure relief
2. As part of the fuel delivery system in the Kart BDC series of carburaters.
Although there considered obsolete they are still available from Elders Rubber in the States as at the request of the Karters there was a limited production run and i believe these new ones don't suffer from the swelling of the origionals and finally disolving into a black gooey mess after some use.
Mc Bob.
1. Inside the fuel cap as a pressure relief
2. As part of the fuel delivery system in the Kart BDC series of carburaters.
Although there considered obsolete they are still available from Elders Rubber in the States as at the request of the Karters there was a limited production run and i believe these new ones don't suffer from the swelling of the origionals and finally disolving into a black gooey mess after some use.
Mc Bob.
