NYC Norton Reed Breather Plumbing

ozcruiser · Mar 3, 2024

The combat breather sits on the bottom of the crankcase so any oil in the crank case will be pushed past the reed valve into the oil tank return line. It can't flow back because of the reed valves so every kick is pumping the oil out of the crank case.

cash · Mar 3, 2024

KiwiShane said:
NYC crank breather install (my vocabulary version)
Remove/ un screw spigot pipe from rear of timing case and block with supplied set screw.
Remove sump plug and screw in NYC Breather plug to check for position of intended return breather pipe that runs from the NYC sump plug up the rear of the engine case (Can readjust if needed to line up perfectly)
Run return NYC hose as per "standard oil circulation" to the neck of the oil tank for unrestricted flow of oil & air.
Connect a hose to oil tank breather outlet to a small air filter or both as I did down to front sprocket.
Depending on what breather filter you use...

With this type of crankcase breather it may make the return side of the oil pump redundant. Perhaps there's potential here to modify/change the oil pump to increase flow and pressure leaving the scavenging to the reed valve.

marshg246 · Mar 3, 2024

cash said:
With this type of crankcase breather it may make the return side of the oil pump redundant.

It absolutely will return oil if the pump is not getting the job done, but you don't want that! The oil filter is on the return side and if the breather is returning the oil the oil filter is not able to do its job.

It did save one guy who had the oil filter gasket in wrong. The oil feed worked fine, but there was no return. He was new to Norton and thought he was seeing oil pump return when he was seeing the breather return the oil. He put quite a few miles on his new build that way.

Tornado · Mar 3, 2024

I recall on one of Dave Sundquist's bikes, he had fit a second filter on the feed side. Something like that could be considered for a sump reed only return I guess.
Are there potential concerns of insufficient sump oil during normal running with a sump reed? Less splash around crank etc. ?

Fast Eddie · Mar 3, 2024

Tornado said:
Are there potential concerns of insufficient sump oil during normal running with a sump reed? Less splash around crank etc. ?

No because there is an upstand tube inside the breather specifically to retain the correct amount of oil in the sump.

cash · Mar 5, 2024

marshg246 said:
It absolutely will return oil if the pump is not getting the job done, but you don't want that! The oil filter is on the return side and if the breather is returning the oil the oil filter is not able to do its job.

Good point. So if the the level of sump oil exceeds the breather header pipe a percentage of the sump oil will bypass the filter. I wonder if it's relevant or not?

robs ss · Mar 5, 2024

I have one of the reed valves on the back of the crankcase (cNw) and love it.
There is some risk of a downside though, I believe. It is an oil filter bypass.
It is the main reason I don't like the Holland Norton Works oil tank check-valve, I have bought one and it replaces the OEM strainer/banjo fitting - except it does away with the strainer. No need for it says HNW.
I disagree as a crank/reed valve may send particulate directly to the oil tank, bypassing the filter. No strainer means these potential contaminates have a free pass to the oil pump.
The risk is very, very low but I don't want any risk of jamming up my oil pump
So - the HNW valve will sit with my spares - unless somebody else wants it!

Cheers

acadian · Mar 5, 2024

Kip said:
Just to clarify - to my way of thinking, aside from the PIA of kickstarting a sumped engine, the real issue on cold starts is "dry" top ends. I don't know if anyone has ever "timed" how long it takes for the circulation of oil to reach the rockers after a cold start, but on Evo Harleys (and others I could name) it is several seconds...plenty of time for trouble with metal to metal.

So, for me the logical extension is if you drain a sumped engine before you try to start it, it would be better to pour a little oil back into the rocker box (and upper cylinders) in addition to the oil tank.

Having a gauge tapped off the rocker feed is quite helpful, with plugs out it takes around 10 kicks to get the needle on the gauge moving and confirm oil up top

NYC Norton Reed Breather Plumbing

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