NYC Norton Reed Breather Plumbing

laurentdom said:
Hi All,

I plan to re-use my current Comstock breather (not sump-type but 1972-type) on a MK3 crankcase, so I'll have the LH case to be milled and drilled accordingly. Can someone give me the dimensions and locations of the 3 holes to drill and mill (one "main", 2 threaded) ?
Thks in advance,
Laurent
Click to expand...

If it's going on a MKIII and you plan on keeping the left hand shift beware of the cross shaft.
 
Lineslinger said:
Thank you all for taking the time to share your insight.

The Mike's XS I have in place is working just fine, no issues.
I was just looking for a solution to draining the sump after the bike has had a long period of sitting.
That's why I was interested in the NYC Nrtn. plug/valve. And also because I continue to get creakier as the years pass and I grow less and less excited about crawling around on the floor and pulling the sump plug.

With the NYC sump breather installed properly, could one disconnect the plugs and crank the E. start a for a few revs to clear excess oil from the crankcase before starting?
Click to expand...
Yes. It does work with the kickstart.

My bike has neither kick or electric start, but I spin my race motor on the rollers to clear the sump if needed.

My breather is the Comstock rear of cases one. Jim had a video somewhere demonstrating clearing the sump by kickstart.

Or to get oil pressure after a rebuild but before 1st start (internal surfaces coated in Graphogen)!
 
If fully wet sumped, tank gauze exposed, then there is essentially nothing in the feed line to pump and no high pressure oil coming out to feed crank and rockers. Makes no difference if the is a sump breather fitted. Cranking or starting in this condition will take a fair while until sufficient oil has returned to tank and made its way back to pressure side of pump. So would be best to check tank level and even drain sump at least partially, tip back into tank to cover gauze.
 
If used correctly the comstock/NYC sump breather will return sumped oil back to the tank if kicked over without the ignition ...and once the gauze feed line is emersed in oil in the oil tank...and again feeding the pump its good to start the engine..
 
Tornado said:
If fully wet sumped, tank gauze exposed, then there is essentially nothing in the feed line to pump and no high pressure oil coming out to feed crank and rockers. Makes no difference if the is a sump breather fitted. Cranking or starting in this condition will take a fair while until sufficient oil has returned to tank and made its way back to pressure side of pump. So would be best to check tank level and even drain sump at least partially, tip back into tank to cover gauze.
Click to expand...
Point taken. However, life is a little different with my Rickman Oil in Frame bike.

Oil drains into the sump by gravity, but with the Rickman you can't get a whole 'tank' full in the sump, because some of it is stored in the lower frame rails hat run below the sump!

And down there is where the feed basically comes from! So when gravity has done it's job, there is still some oil around the pick up.

But, in any case you need to be realistic about the flow rate, particularly of cold oil. And including the fact that there is some oil in the crank and galleries.
 
Some "stuff" RE: NYC breather. I installed mine and found it was leaking from the small Allen screws that hold the cap on the body - notably the two opposite the return line - they were loose, the others tight. It pays to double-check, although one shouldn't need to on a $330 part!

Since it has not been and will not be started for some time - I'm wondering if it makes sense to pull a rocker box cover and spark plugs and manually "oil" the top end a little in that manner to save 'scuffing' and dry rubs when the day comes to kick it over for the first spring ride. I have more faith in the "cling" of synthetic oil than regular....but knowing that 80-90% of the wear comes from starting....and wanting to minimize metal to metal after a long "hibernation" it seems like cheap and worthwhile 'insurance' for old engines that use thicker viscosity lubricants.
 
Lineslinger said:
Thank you all for taking the time to share your insight.

The Mike's XS I have in place is working just fine, no issues.
I was just looking for a solution to draining the sump after the bike has had a long period of sitting.
That's why I was interested in the NYC Nrtn. plug/valve. And also because I continue to get creakier as the years pass and I grow less and less excited about crawling around on the floor and pulling the sump plug.

With the NYC sump breather installed properly, could one disconnect the plugs and crank the E. start a for a few revs to clear excess oil from the crankcase before starting?
Click to expand...
There is a very simple, low cost way to manage the wet sumping issue. Simply siphon warm oil from the oil tank before oil migrates past the pump. Get yourself a foot or so of steel pipe to reach the bottom of the oil tank push some plastic tube onto the pipe and siphon the oil into an oil container. Tie the key to the oil container so there is no chance of a dry start and consider a syringe of oil down the pushrod tunnels (to lube cam etc) when you put the oil back in.
 
Not a problem if you live in Southern California. Other locations may be a bit of a bother.
 
Following up on Kip's mention of tightening up the hex bolts - Kenny confirms that the hex wrench size is 9/64" for this task.

EDIT: NYC breather tight and right - moving up the engine now to see where the oil is coming from.
 
Last edited:
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.
 
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.
Click to expand...
The crank seal at the primary can blow from too much lower end pressure...
 
@Jdub, I had a problem with a kit I purchased around March of 2023 where it leaked at the breather hose junction. I found, and Kenny confirmed, that the machined surface cut into the breather body was slightly smaller than the supplied copper washer causing the banjo fitting to not seat flush with the body. Result was a small leak; you could see the problem when you got up close to it. Kenny quickly sent me a replacement body which works fine now. and I believe he said he had correctly sized washers on order that would also solve the problem.
 
MichaelB - possible, not probable, or likely. A drained battery, right leg cramp, or coughed-up lung is a more common outcome. Best to drain/replace the oil before any of that, no matter how you start the bike. Whereas the cold start wear and tear issue is a given.
 
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.
Click to expand...
I don't see why, the supply to the oil pump from the oil lines from the oil tank is still full of oil.
 
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.
Click to expand...
Kip,
The factory also says to put some oil into the intake rocker box after draining the motor. I put in about 6-7oz. in mine.Doesn’t take that long.
Mike
 
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.
Click to expand...
The rockers are fed at the same pressure as the crankshaft. As a bike sits, that line empties. If wet sump'ed, there a good chance it's already empty - nothing to do with draining the sump.

The rocker feed lubricates the rocker spindles. A little oil gets on the valve stems and springs. The oil in the intake side drains into the timing area. The oil in the exhaust area drains down on the tappets and therefore on the cam. All those things should still have a coating of oil, so a short delay isn't a problem, and the delay is actually very short.

IMHO it is not needed, but it would not hurt to pour oil in all three the rocker areas, I would not put any in the cylinders.
 
@marshg246 : Reply #37

+1

When we were kids, we once took an old Dodge with a flathead six engine, drained the oil, then placed a brick on the accelerator. We thought the engine would spectacularly explode. It ran for perhaps 40 minutes, then just slowed down and stopped. Next day, after cooling down, it cranked right up.
This illustrates the lubricating effect of that residual oil film.
So, I would contend, making much of starting an engine after a long shutdown, is much ado about nothing.

Slick
 
Last edited:
texasSlick said:
@marshg246 : Reply #37

+1

When we were kids, we once took an old Dodge with a flathead six engine, drained the oil, then placed a brick on the accelerator. We thought the engine would spectacularly explode. It ran for perhaps 40 minutes, then just slowed down and stopped. Next day, after cooling down, it cranked right up.
This illustrates the lubricating effect of that residual oil film.
So, I would contend, making much of starting an engine after a long shutdown, is much ado about nothing.

Slick
Click to expand...
So, You really liked that old Flat head, eh? :D:D
 

Similar threads

Bonzo
Comstock / NYC Norton reed breather banjo washer size?
Replies
3
Views
473
Bonzo
Bonzo
Bonzo
A quick NYC/Comstock Reed Breather Valve Question...
Replies
19
Views
1,163
Mart UK
Mart UK
Burgs
  • Locked
trials and Tribulations (reed Breather and Exhaust)
Replies
18
Views
1,962
robs ss
robs ss
comnoz
  • Locked
case reed breather
2
Replies
37
Views
5,320
comnoz
comnoz
gortnipper
  • Locked
Mounting Mike's XS reed breather
2
Replies
27
Views
5,396
swooshdave
swooshdave
Back
Top