Reed PCV valve

texasSlick · Nov 19, 2015

pete.v said:
I don't see the need to eliminate the timed breather to add something else. I run 2 reed breathers. One off the lower rear left up to under the seat where it take the natural right angle to the oil tank, and another reed(from Grandpaul) off the timing side it the old mag area, or the proposed start area the never transpired. It all depends who you talk to. Anyhow, it doesn't matter.

The point is, if one is good then why not 2. People wonder if it is better to go off the crankcase or the timing chest. I say both.

I agree ... two cannot hurt, and are likely better than one. However, the timed breather must be fitted with a reed valve, because IMO, it is not optimally effective as is .... it lets air back into the crankcase despite its valve action. If it were effective, there would be little or no improvement adding a reed valve elsewhere. Thus, I say to block it off and place a reed valve (or two) somewhere else . Fitting the timed port with a reed valve should improve its action, but it will be more effective if you follow jseng1 suggestion to remove the rotating plate, etc.

Slick

danfr · Nov 21, 2015

I ordered up two PCV Valves. I'll have the timed breather up to the oil tank and I'll run a breather line from the timing side of the case temporarily to a vented can. Once I don't see any oil in the can, I'll route the breather line down to the gap near the gear box.

cheers

grandpaul · Nov 21, 2015

danfr said:
Once I don't see any oil in the can, I'll route the breather line down to the gap near the gear box.

Leave the catch can. Any time your oil tank drains enough oil down to your sump, you'll puke oil all over the ground as soon as the engine starts. If you don't happen to notice it, you'll wet down your rear tire & brake as you are riding along. Perfect recipe for a salvage rebuild!

o0norton0o · Nov 21, 2015

danfr said:
I ordered up two PCV Valves. I'll have the timed breather up to the oil tank and I'll run a breather line from the timing side of the case temporarily to a vented can. Once I don't see any oil in the can, I'll route the breather line down to the gap near the gear box.

cheers

...OR you just just put a "T" in the return line from the timed breather port and join both hoses to breath into the oil tank.... (like I did on my '70 ) This way you don't piss oil on your rear tire or the underside of your bike...

aceaceca · Nov 21, 2015

By dumping crankcase vapors into the oil tank you are just adding contaminants to your oil. Water vapors, unburned hydrocarbons, and evaporated fuel that has gotten past the rings from tickling the carbs and such. Makes no sense. You are saving the earth and killing your Norton.

ashman · Nov 22, 2015

I run a large catch can (bottle) between my engine mount (2 litres) which has a few air holes in the top to relive the pressure, the mount of oil it leaves in the bottle after 1 year of use is very minimal, I have been doing this for over 35 years and you don't cominate the oil in your oil tank and no mess on your rear tirer.

Ashley

MFB · Nov 22, 2015

aceaceca said:
By dumping crankcase vapors into the oil tank you are just adding contaminants to your oil. Water vapors, unburned hydrocarbons, and evaporated fuel that has gotten past the rings from tickling the carbs and such. Makes no sense. You are saving the earth and killing your Norton.

+1 on that. It makes no sense to dump blow-by from the crankcase into the oil tank unless the breather system carries a significant amount of oil.
I blanked off my timed breather and went over to timing case breathing into a catch tank via an XS650 reed valve. This also enabled me to vent the oil tank via the original breather port and so plug the troublesome tube that drips oil into the air filter. All good.

JimC · Nov 22, 2015

MFB said:
aceaceca said:

By dumping crankcase vapors into the oil tank you are just adding contaminants to your oil. Water vapors, unburned hydrocarbons, and evaporated fuel that has gotten past the rings from tickling the carbs and such. Makes no sense. You are saving the earth and killing your Norton.

Click to expand...

+1 on that. It makes no sense to dump blow-by from the crankcase into the oil tank unless the breather system carries a significant amount of oil.
I blanked off my timed breather and went over to timing case breathing into a catch tank via an XS650 reed valve. This also enabled me to vent the oil tank via the original breather port and so plug the troublesome tube that drips oil into the air filter. All good.

I believe every road going engine manufactured in the U.S. since 1967 has been venting the crankcase back into the oil supply. That's when the road draft tube was eliminated in favor of the PCV valve. Although, the majority of those engines were not dry-sump engines. I can see why one would think a catch can is better than venting back to the oil tank, but I'm not sure that is so.

MFB · Nov 22, 2015

JimC said:
I believe every road going engine manufactured in the U.S. since 1967 has been venting the crankcase back into the oil supply. That's when the road draft tube was eliminated in favor of the PCV valve.

I don't think that's right. The road draft tube vents the crankcase directly to atmosphere. The PCV ("v" for ventilation) valve vents it to the intake manifold to be burnt in the high temperature incinerator called the combustion chamber.
In both cases the contaminants are REMOVED from the oil supply.
In the case of our dry-sumped Nortons, it seems illogical to deliberately direct these contaminants to the separate oil supply.

texasSlick · Nov 22, 2015

Quote:

"in the case of our dry-sumped Nortons, it seems illogical to deliberately direct these contaminants to the separate oil supply."

IMO:

Dry or wet sump is irrelevant .... the oil gets exposed to blow-by gasses regardless, and as well, regardless of where the crankcase is vented.

A wisp of blow-by gas above the oil in the tank, is not likely to contaminate the oil anymore than when the same oil was blasted into a mist in the crankcase.

I think this is a non-issue ... much ado about nothing. If it is a big deal, what are those who think so, doing about the four wheeled vehicles they drive ... the blow-by gas is in the oil reservoirs of those vehicles, and unlike our Nortons, that oil reservoir is in a constant agitated, mixing, and gas absorption condition.

Slick

JimC · Nov 22, 2015

MFB said:
JimC said:

I believe every road going engine manufactured in the U.S. since 1967 has been venting the crankcase back into the oil supply. That's when the road draft tube was eliminated in favor of the PCV valve.

Click to expand...

I don't think that's right. The road draft tube vents the crankcase directly to atmosphere. The PCV ("v" for ventilation) valve vents it to the intake manifold to be burnt in the high temperature incinerator called the combustion chamber.
In both cases the contaminants are REMOVED from the oil supply.
In the case of our dry-sumped Nortons, it seems illogical to deliberately direct these contaminants to the separate oil supply.

You are correct on were the PCV vents to. I was thinking more of closed circuit venting rather than external. I rather discounted the burning process. Slick points out that the oil is already contaminated with blowby, regardless how the crankcase is vented. I agree with him, oil tank or catch can, little if any difference. The catch can is more of a placebo. Lot of that goes on here.

Onder · Nov 22, 2015

Placebos often make you feel better

My 850 is covered with them!

JimC · Nov 22, 2015

Onder said:
Placebos often make you feel better
My 850 is covered with them!

I have some myself. Change oil and filter, adjust timing and carbs, check tire air pressure and you KNOW that sucker is at least a 1/2 second faster in the 1/4 mile.

grandpaul · Nov 22, 2015

If I can eliminate a bit of contaminants and moisture without any effort other than occasionally dumping a small catch bottle, I have reduced the potential for damage just that little bit more.

It is certainly better than allowing it back in the tank. After all, it is typically more residual condensate/moisture and contaminant than oil.

swooshdave · Nov 22, 2015

I run my reed valve back to the tank. When it wet sumps I can kick it a few times and the extra oil is pushed out of the crankcase and back to the tank.

MFB · Nov 23, 2015

grandpaul said:
If I can eliminate a bit of contaminants and moisture without any effort other than occasionally dumping a small catch bottle, I have reduced the potential for damage just that little bit more.

It is certainly better than allowing it back in the tank. After all, it is typically more residual condensate/moisture and contaminant than oil.

+1 again.
And this placebo has another real benefit of freeing up the top port on the oil tank for tank ventilation so that a real and present problem can be solved, that of the tube which drips oil into the air filter. Its I.D. is just right to take a 5/16 UNF thread so that it can be plugged by loctiting a bolt in it.

Onder · Nov 23, 2015

Guilty of wandering thread subject but I run the Comnoz sump reed back to the tank. The vent on
the top of the tank just has a short hose run down the frame tube and tie wrapped. Rarely if ever
is there any drip from it. Was reluctant to pipe it to the date box but I probably will now.

grandpaul · Nov 23, 2015

swooshdave said:
I run my reed valve back to the tank. When it wet sumps I can kick it a few times and the extra oil is pushed out of the crankcase and back to the tank.

"Wet sumping" is a whole other issue that the reed valve shouldn't have to deal with. The way I mount them, they are very effective, and do NOT pass "sumped" oil back to the tank; that has to be done by other means until the actual cause is remedied.

jaguar · Nov 23, 2015

Grandpaul,
can you post a link to the "$25 Reed valve" that you recommended to me on CR.net?

grandpaul · Nov 23, 2015

jaguar said:
Grandpaul, can you post a link to the "$25 Reed valve" that you recommended to me on CR.net?

I thought it was in this thread, there are typically 2 or 3 crankcase breather threads happening at any given time on this forum.

I have 5 or 6 on the shelf.

Reed PCV valve

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