One way breather valve differences

Status
Not open for further replies.

highdesert

Joined
Jun 17, 2009
Messages
642
Three months ago I put in the breather line on my 73 850 the XS650 valve. Worked great, as in stopped every last little oil leak.
This valve takes a bit of blowing effort to open, and you cannot suck back at all, mouth test.

During a routine inspection, I discovered emulsified oil in both the breather line and also throughout the valve.
It also seems to require more effort, mouth test, to make it open, and when put in place with the motor idling, making a slight "honking" noise now.

Hearing about the Dorman brake check valve being a little weaker, easier to open, I bought one.

Is this thing defective? I can blow in the bigger diameter hole just fine, easier in fact than the XS650 valve, but can also suck air back, slightly more effort.
This is the opposite of the XS valve, no suck back.
Is this normal?
Shouldn't the motormite also not allow air to be sucked back, or it is just so much weaker, for our norton breather purposes, that is does not matter?
thanks for any comments
 
I believe that to be a bad valve. I am into my third year with mine. Resently tested. Working perfect.
 
Have a look at a Standard Motor Products AV13 next time you're at the auto parts store. They require some modification to make a stepdown barb for the output, but it's all available in brass from the hardware store.
 
highdesert said:
Three months ago I put in the breather line on my 73 850 the XS650 valve. Worked great, as in stopped every last little oil leak.
This valve takes a bit of blowing effort to open, and you cannot suck back at all, mouth test.

During a routine inspection, I discovered emulsified oil in both the breather line and also throughout the valve.
It also seems to require more effort, mouth test, to make it open, and when put in place with the motor idling, making a slight "honking" noise now.

Hearing about the Dorman brake check valve being a little weaker, easier to open, I bought one.

Is this thing defective? I can blow in the bigger diameter hole just fine, easier in fact than the XS650 valve, but can also suck air back, slightly more effort.
This is the opposite of the XS valve, no suck back.
Is this normal?
Shouldn't the motormite also not allow air to be sucked back, or it is just so much weaker, for our norton breather purposes, that is does not matter?
thanks for any comments
Click to expand...

Reed valves like the XS650 one are extremely resistant to backflow. Common flapper valves like the Motomite are not.

To prevent the oil buildup past the reed valve there are two options, place the valve high enough that the oil will most likely not reach it or provide a small drain hole next to the reed valve to allow the oil to drain back. This is what I believe Ducati does with their crankcase-mounted reed valve (BMW uses a similar setup, I believe, but their reed valve is situated on top of an air chamber which "filters" the oil out). Now you may think that a small hole would defeat the purpose of the reed valve but this is, in fact, not what happens. The air pressure finds the path of least resistance (the reed valve) and not the tiny drain hole (high resistance).

Once the engine shuts down, the oil will drain back through the oil into the crankcase. That is the theory I'm subscribing and will drill a hole when I'm ready to mount the XS650 valve close to the engine.

One way breather valve differences
 
Dave, an 850's breather is up high on the timing case and emulsified oil is infused with water and should not be aloud to return anywear but outside the system.
 
pvisseriii said:
Dave, an 850's breather is up high on the timing case and emulsified oil is infused with water and should not be aloud to return anywear but outside the system.
Click to expand...

On the stock 850 breather I wonder if there is enough pressure to push the emulsified oil out far enough.

This is theoretical but wouldn't any water in the oil vaporize when the oil got hot enough and be forced out the breather. Isn't this why you often hear that it's best to get the engine nice and hot to get rid of the condensation (especially useful if you have a vehicle in storage and want to start it occasionally)?
 
I don't know, but I got emulsified oil all the way through the XS650 valve and right up to the end of the oil tank tube inside the oil tank, so it must be
under some pretty good pushing pressure to get that far
 
highdesert, I think this condition (Emulsafied oil in the lines) exsists from the lack of breathing. What were the oil leaks that were eliminated by the device? The only one I had was the crank seal. And yes, you do have to get the oil hot once in a while. It take a pretty good ride(at lease a half on hour) to get the oil warm much less hot.
 
This also happens on my Buell, And it has no one way valve on it. What I was told on a Buell forum is that this is normal and happens because when the bike cools damp air is drawn into the motor and condensation occurs. Also I have heard that is why we see rust inside the transmission parts, It is also caused from the same. You guys can check me on this but some people seemed like "You don't know that" When I asked this question awhile back. If you take short rides and don't give the oil a chance to boil off the moisture it will be even worse over time.
 
Anyone have a motormite valve lying around?

Can you tell me if it is a complete one way valve, in that it does not allow any, none, blowing back air on the leeward side, like the XS valve does?
 
Mine is a complete one way valve, They are meant to be one way valve. If you can blow through the small end, it is bad.

Can we have some other people confirm this for highdesert please.
 
Only passes air one way on my spare brand new Motormite. Test was blowing and sucking on the larger barbed end (which faces the engine when installed). I turned red in the face and the veins were popping out on my forehead...

Russ
 
I was brought up to believe that the cure for emulsified oil is to ride the bike harder for longer.

What you're describing is exactly what drips out of my T140 breather pipe on the first couple of rides of the year.

Not sure the breather is an issue beyond being a bit clagged up through cold weather use?
 
That enough proof for me, this new motormite is going back to be exchanged. It is clearly defective. Thanks everyone!
 
batrider said:
I turned red in the face and the veins were popping out on my forehead...

This happens to me when I try to explain the importance of having motorcycles to the wife sometimes, LOL. :lol:
Click to expand...
 
I thought the Motormite worked until I started to run a belt primary. It's pretty hard to tell if it's working if you have a chain drive primary. In my case, the Motormite provided a placebo effect only. Any oil in the valve renders them less effective.They are designed for a dry, steady vacuum pull, not an oily, alternating vacuum/pressure at a frequency of 80+ cycles per second.
 
JimC said:
They are designed for a dry, steady vacuum pull, not an oily, alternating vacuum/pressure at a frequency of 80+ cycles per second.
Click to expand...

Unlike a reed valve which can operate at those frequencies.
 
If you're choosing a valve - look at big singles or twins that have both pistons decending at once like the BMW boxer. Other layouts don't have the same requirements (harleys and ducks are close).

I tried mounting an auto EGR reed valve years ago hoping it would help pump oil out of the sump. Worked great at idle & low revs but did absoutely nothing at higher RPM - didn't seem to be able to respond fast enough when buzzing or the air didn't have time to reverse or pulsate at RPM. It seemed completely worthless for a racer so I pulled it.

I'm trying to keep an open mind about this - convince me of its real value compared to enlarged breather ports into the timing cover & exit etc.

And if it takes pressure to open that valve - doesn't the valve momentarily add to crank case pressure?

Jim
 
swooshdave said:
JimC said:
They are designed for a dry, steady vacuum pull, not an oily, alternating vacuum/pressure at a frequency of 80+ cycles per second.
Click to expand...

Unlike a reed valve which can operate at those frequencies.
Click to expand...

If your running at that frequency for vary long ain't nothing gonna stop oil from blowing through somewhere. Besides 850's aren't as succeptable to the crank pressure problems of the 750's. Cranks seals are only $3 and easy to change. Changing one every 5 thou or so should be considered a standard Maintanance practice.
Highdesert, if I were you, I would pull that thing off return it for a refund and ride on to the tavern buy a couple beers with the refund.....only a couple though.
My humble opinions.
 
80 cycles per second is only 4800 rpm. Sounds like normal cruise to me. Jim
 
Status
Not open for further replies.
Back
Top