Oil tank vent options

is the reed valve some have recommended installed in the vent line between the oil tank and breather?
 
10drum said:
is the reed valve some have recommended installed in the vent line between the oil tank and breather?
Click to expand...
That's one way if the reed valve is a type with inlet at bottom and outlet at top, others take over the place of the original breather at the back of the crankcase.
 
kommando said:
That's one way if the reed valve is a type with inlet at bottom and outlet at top, others take over the place of the original breather at the back of the crankcase.
Click to expand...
Thanks, I was wondering iI I would need to replace the stock breather on the crankcase. I've built a few BMW air heads and they have a reed type crankcase vent.
 
ilikevelos said:
I think the vent line in Lioneslingers photos is too short to buffer the pressure pulses. Many Velocettes use a line from engine to oil tank and a line along the fender as you suggest. It is well known that the length of the lines is rather critical to tuning the vent system to work properly. I surmise that changing the length of the line may improve the amount of mist experienced. That said, I use a xs650 reed valve between the tank and engine vent.

Best to all.
Click to expand...
Line length is not an issue. You are way overthinking it.
It is simply another step is alleviating any potential pressure buildup in the oil tank and crankcase.
I only posted a couple of reference photos, thus you are passing judgement on one pixel of a much bigger picture. If you are misting oil on the rear of your frame/fender/back tire I suggest that is a problem. There should not be any oil exiting the system that far from the tank outlet/port.
I run my oil level on the low mark of the stick and don't have any overflow or misting issues. The oil pulses you refer to are not exactly blasting into the tank. I rebuilt the oil pump during restoration and it is functioning as it should.

The total configuration of all crankcase vent and circulation lines plumbed together properly has performed without issue since I installed them 6 years ago.
 
Last edited:
Lineslinger said:
Line length is not an issue. You are way overthinking it.
It is simply another step is alleviating any potential pressure buildup in the oil tank and crankcase.
I only posted a couple of reference photos, thus you are passing judgement on one pixel of a much bigger picture. If you are misting oil on the rear of your frame/fender/back tire I suggest that is a problem. There should not be any oil exiting the system that far from the tank outlet/port.
I run my oil level on the low mark of the stick and don't have any overflow or misting issues. The oil pulses you refer to are not exactly blasting into the tank. I rebuilt the oil pump during restoration and it is functioning as it should.

The total configuration of all crankcase vent and circulation lines plumbed together properly has performed without issue since I installed them 6 years ago.
Click to expand...
Velo's recommendation re the length of line, as I understand it, was to tune the system so oil vapor was not blown. No reed valve or PCV was used by them and no filter on the line.

Apparently Norton used different length oil dipsticks. Mine was short. At the time I just followed the line on the dipstick, Now I would not fill the oil tank that full, understanding the need for airspace in the tank. Learn through (sometimes painful) experience.
 
10drum said:
Greetings,

I have a 72 Interstate.

Currently I have the oil tank vented with an 8" length of tube to a small filter behind the battery box, it's gets kinda messy back there.

I'm a triumph guy, and I route the crankcase/oil tank vents on my triumphs under the rear fender to the back of the bike.

Has anyone done that with the Norton oil tank vent?

Thanks for all replies.

Phil
Click to expand...
Yes.
Oil tank vent options
Oil tank vent options
 
See: https://andover-norton.co.uk/files/0c4/WEBSHOP VERSION Norton Commando Oil tank dipsticks AN.pdf

Most agree that you should keep the oil level between the low and high mark. Since the low mark is the same on both, keeping it in the middle of the low and high mark means no trouble with either. Keeping it at the high mark for the earlier stick is generally too high.

If more than a tiny bit of oil is coming out the oil tank vent on the side mounted oil tanks, then the problem with that bike should be investigated - it's not normal as there should be no atomized oil above the oil level in the tank. Unlike a Triumph, the oil return oozes into the oil tank. If the pump is not working well and you have a reed valve breather, the oil will come into to the neck of the oil tank with great force and that could put droplets of oil in the air. Of course, that's is pointing away from the vent and is several inches away as well.

The square tanks are a different subject. If you have the kind with the breather in the froth tower, then you DO NOT want a reed valve breather. The breather will shoot oil across the top of the vet and drain lots of oil into the air cleaner. The kind with the breather into the top of the tank away from the froth tower does not have that problem.
 

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