650ss/750 atlas crankcase breather questions and confusion

seanalex

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I've been looking high and low for a photo of how what I believe is the crankcase breather attaches to the case. I've looked through all the different AN drawings for the heavy twins motors, and I can't see any that have this fitting to where the breather pipe would attach.

Finally I've come across a set of cases for sale on eBay here, which have a photo of the backside of these cases.



650ss/750 atlas crankcase breather questions and confusion



My motor is of course the basket case variety, and when I received it, the rear of the case looked like this.

650ss/750 atlas crankcase breather questions and confusion


Does anyone know what this vent is? Or where to find the fitting that would thread into this? The motor on Ebay seems to be a bit newer than mine, my serial is 101,xxx, and the Ebay one is 117,xxx
 
Atlas c/c have a different system, pipe is at the end of camshaft though an elbow connector.
650 can be in a couple of different places, Norton changed them over the years, as they did the oil tank when they went to a tower on top of it. It was all improvement as they went along.
 
650 can be in a couple of different places, Norton changed them over the years

Bernard, surprised to hear this. Just took a quick peek in the office to see all my NHT 49 52 53 57 59 61 63 engines.(and my friends manxman) only the last 2 are 650 and yet all case attachment points look like the top pix. Is it the coupler and hose that changed?
 
Essentially it is a copper or similar tube brazed to a tab and protrudes into the case approx 1/4” (?) held in place by the slotted screw for crankcase breathing. There is a small gasket placed between the tab and case. Could be easy enough to make if you couldn’t find one or in the interim.

Two part numbers found: 24313; 19382A
Screw: T2213
Gasket: 22240
 
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Essentially it is a copper or similar tube brazed to a tab and protrudes into the case approx 1/4” (?) held in place by the slotted screw for crankcase breathing. There is a small gasket placed between the tab and case. Could be easy enough to make if you couldn’t find one or in the interim.

Two part numbers found: 24313; 19382A
Screw: T2213
Gasket: 22240
Thanks for the part numbers. I do see now that Norvil sells the whole unit, and screw.
 
The breather for this bike, with its "bowtie" rotating windows on the end of the camshaft has very little capacity to lower peak crankcase air pressure.
For your consideration: I purchased a set of orphan case online (keep my matching numbers cases untouched) and drilled and ground holes in the rear to take a reed valve set-up, similar to Jim Comstock's. Very much more effective in reducing peak pressure - and leaks.
I run the existing system in parallel - but 90% of the work is done by the reed valve.
 
The breather for this bike, with its "bowtie" rotating windows on the end of the camshaft has very little capacity to lower peak crankcase air pressure.
For your consideration: I purchased a set of orphan case online (keep my matching numbers cases untouched) and drilled and ground holes in the rear to take a reed valve set-up, similar to Jim Comstock's. Very much more effective in reducing peak pressure - and leaks.
I run the existing system in parallel - but 90% of the work is done by the reed valve.
Sounds interesting. Do you have photos of how you've done this somewhere?
 
When I sent the bottom end of my ‘59 Model 99 to Jim for machine work he gave me the option of threading the breather hole and plugging then using one of his large sump plug type reed breathers to improve crankcase gas release. I opted to stay with the original set up.

If I had a Slimline bike and oil tank, or had not already had my Wideline oil tank cleaned and painted I would have put a fitting to accept the hose from the reed breather and went that route.
 
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