case reed breather

comnoz · Oct 20, 2016

I nearly did not post this as I do not want people to think I am promoting my own products or attacking JS.
I have more work than I can handle and there is room for more suppliers.
I do appreciate JS's enthusiasm and what he is trying to do.

But I do have some info that should be out as I hate to see people making the same mistakes I made.

Here is a picture of the engine cases that I am using on my spintron.

As you can see they have been modified for a reed breather very similar to what JS has designed.

This was an early attempt at building a reed breather for my bike.

When the crankcase was evacuated of air -without evacuating the timing chest also -the air ended up traveling up the intake spring drain hole to get back into the crankcase. When the air was moving up, the oil could not drain from the spring area and I ended up with too much oil around the intake springs and I had a smoky exhaust after a few highway miles.

The next step I did to cure this was to plug the head drainback hole into the timing chest and redrill it so the oil went directly into the crankcase. That cured the smoking but on the next substantial road trip the intermediate gear seized to the pinion shaft. It became obvious that the timing chest depended on the oil from the cylinder head drain to provide lubrication. Jim

swooshdave · Oct 20, 2016

I still don't see why people insist on breathing through the timing chest. Sure Norton put a breather on it but they didn't have anyone half as smart as Jim. :mrgreen:

Kvinnhering · Oct 20, 2016

Good to know. Thanks for the information.

grandpaul · Oct 20, 2016

I always thought Jim had tested this stuff out, sure enough. I think there was even testing done with a plexi or windowed cover to observe oiling and oil migration?

There is NO drawback to mounting a reed EXTERNALLY to the back of the timing chest. It certainly DOES NOT exacerbate any existing oil weepage. Also, it in NO WAY affects cam drivetrain oiling.

comnoz · Oct 20, 2016

grandpaul said:
I always thought Jim had tested this stuff out, sure enough. I think there was even testing done with a plexi or windowed cover to observe oiling and oil migration?

There is NO drawback to mounting a reed EXTERNALLY to the back of the timing chest. It certainly DOES NOT exacerbate any existing oil weepage. Also, it in NO WAY affects cam drivetrain oiling.

I agree. Jim "Comnoz"

Robert_Norton · Oct 20, 2016

grandpaul said:
There is NO drawback to mounting a reed EXTERNALLY to the back of the timing chest. It certainly DOES NOT exacerbate any existing oil weepage. Also, it in NO WAY affects cam drivetrain oiling.

Has it been definitively determined that the aftermarket breathers, for the back of the timing cavity, do do something that's positive for the operation of the engine? Is it known how effective they are in comparison to the two products Mr. Comstock produces? I assume they are not as effective, otherwise I doubt Mr. Comstock would have developed his two options, for the back of the cases and beneath.

I read all the associated threads when they were new, saw the "MikeXS650" breather(s) and similar types mentioned, maybe in the same thread(s), but can't remember if it was determined exactly how they compare in terms of the advantages and vacuum pulled to the Comstock models.

Appreciate all the exchange and sharing of information here, from everyone.

.

comnoz · Oct 20, 2016

Robert_Norton said:
grandpaul said:

There is NO drawback to mounting a reed EXTERNALLY to the back of the timing chest. It certainly DOES NOT exacerbate any existing oil weepage. Also, it in NO WAY affects cam drivetrain oiling.

Click to expand...

Has it been definitively determined that the aftermarket breathers, for the back of the timing cavity, do do something that's positive for the operation of the engine? Is it known how effective they are in comparison to the two products Mr. Comstock produces? I assume they are not as effective, otherwise I doubt Mr. Comstock would have developed his two options, for the back of the cases and beneath.

I read all the associated threads when they were new, saw the "MikeXS650" breather(s) and similar types mentioned, maybe in the same thread(s), but can't remember if it was determined exactly how they compare in terms of the advantages and vacuum pulled to the Comstock models.

Appreciate all the exchange and sharing of information here, from everyone.

.

The testing I have done shows the case reed breather draws a little deeper depression than a breather attached to the timing chest. It will also continue to draw a depression to a higher RPM.

In reality the difference in leak prevention is very small.

The biggest benefit to my breather is rapid clearing of the excess oil in the cases after a wet sump condition or a long period of idling. Jim

L.E.N. · Oct 20, 2016

Is the concern about wet sumping that it is hard to kick through the first startup of the day or is there something else I'm missing here? My bike never leaks and has no breather that I am aware of, engine # 305750
Lance

comnoz · Oct 20, 2016

L.E.N. said:
Is the concern about wet sumping that it is hard to kick through the first startup of the day or is there something else I'm missing here? My bike never leaks and has no breather that I am aware of, engine # 305750
Lance

If the engine is started when there is too much oil in the crankcase then the rings get flooded and smoke out the exhaust for the first couple minutes is the result. It is tough on spark plugs too.

My breather will not help with the hard kick though when the crankcase is full and the weather is cool or you are running straight weight oil. Jim

Robert_Norton · Oct 20, 2016

L.E.N. said:
Is the concern about wet sumping that it is hard to kick through the first startup of the day or is there something else I'm missing here? My bike never leaks and has no breather that I am aware of, engine # 305750
Lance

Probably get different answers for that question, depending on how old someone is, or how strong their knees and legs are. For me it would be avoiding the unpleasant experience of blowing out the crankcase seal on the primary side of the cases. I haven't had a bike running in a long time, but if/when I get back to the point where I've got one in operation, I'd probably drain the motor before risking starting one that was wet-sumped.

I've never had a primary case seal fail due to wet-sumping, but back when I was younger and had a bike running, it would never sit long enough to wet-sump.

.

comnoz · Oct 20, 2016

Robert_Norton said:
L.E.N. said:

Is the concern about wet sumping that it is hard to kick through the first startup of the day or is there something else I'm missing here? My bike never leaks and has no breather that I am aware of, engine # 305750
Lance

Click to expand...

Probably get different answers for that question, depending on how old someone is, or how strong their knees and legs are. For me it would be avoiding the unpleasant experience of blowing out the crankcase seal on the primary side of the cases. I haven't had a bike running in a long time, but if/when I get back to the point where I've got one in operation, I'd probably drain the motor before risking starting one that was wet-sumped.

I've never had a primary case seal fail due to wet-sumping, but back when I was younger and had a bike running, it would never sit long enough to wet-sump.

The only time I have seen a crank seal blown out by starting when wet sumped was when it was a loose fit to begin with.
If the seal is tight and/or installed with a little epoxy then there is no worries. Jim

.

Robert_Norton · Oct 20, 2016

Mr. Comstock,

Thanks for so generously sharing all your knowledge! It's hard to wrap the mind around how much valuable information you've so freely shared on accessnorton.

.

L.E.N. · Oct 20, 2016

I'm 63 years-old and the 1st kick through can be a real bear. Is it really recommended to drain the sump and replace the oil in the tank or just kick on through like I've always done. It almost always starts 1st kick even when cold and hard to kick. Never kicks back, old analog Boyer.
Lance

comnoz · Oct 20, 2016

L.E.N. said:
I'm 63 years-old and the 1st kick through can be a real bear. Is it really recommended to drain the sump and replace the oil in the tank or just kick on through like I've always done. It almost always starts 1st kick even when cold and hard to kick. Never kicks back, old analog Boyer.
Lance

My bike has always wet sumped completely in about a weeks time. I have never drained the sump before starting. One kick and I bring it to a fast idle. In about 10 seconds the sump is cleared through the reed breather.

There wouldn't be a problem even without the reed breather other than dirty plugs and combustion chambers. Jim

seattle##gs · Oct 21, 2016

would your breather help with ring break in on a fresh motor?

Fast Eddie · Oct 21, 2016

seattle##gs said:
would your breather help with ring break in on a fresh motor?

I gotta ask... how?

What is your hypothesis as to how it can influence / benefit ring break-in?

I can't see the link.

seattle##gs · Oct 21, 2016

With the crankcase being pressurized it might be trying to blow air upwards past the rings and not allowing them to seat as readily. If the crankcase pressure is removed then there would be less resistance to the rings seating. There can be blowby going up as well as down in the critical few miles while the rings are trying to bed in.

74 Lloydy · Oct 21, 2016

Hi Gents

Is this a reed valve in the picture.

L.E.N. · Oct 21, 2016

Thanks Jim, that's what I wanted to know.
Lance

comnoz · Oct 21, 2016

Fast Eddie said:
seattle##gs said:

would your breather help with ring break in on a fresh motor?

Click to expand...

I gotta ask... how?

What is your hypothesis as to how it can influence / benefit ring break-in?

I can't see the link.

Ring seating would be helped by having a higher pressure differential across the ring. So I suppose in a tiny way the reed breather may help seat the rings.

case reed breather

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