Unraveling the 961 part two (oil in the air box)

Just to be clear. Currently I have a clear silicone tube running from the crankcase breather into the RH rocker cover - most of the oil travelling up the tube will just drain back into the sump to be scavenged - so the rocker cover/valve gear will be acting as an oil separator. I'll wait to see how much oil exits via the LH rocker cover banjo bolt into the oil separator before deciding what to do. As the oil separator is a reasonable distance from the rocker cover any moisture and other combustion products will probably condense, which I wouldn't want returning to the engine. If so I'll need to try plan b, c, d etc or just empty it when required.
 
Jim Schmidt put this video on YouTube showing the stark difference a reed valve makes in the breather. I reckon it wouldn't do any harm to try one on a 961. (If I had a 961 i'd definitely do it)



Cheers,

cliffa.
 
Remember that the frame oil tank must vent also. If I was putting in the one way valve , I would look into routing the frame tank vent to a filter. Or if you are already doing the IAC blocking then route the frame breather to the now unused IAC to air box fitting . Old Nortons have a separate oil tank vent lets not forget that. Now the only oil coming out of the frame oil tank vent will be when overfilled or super downhill and braking. Then I would still run a catch bottle just in case you get oil in the airbox. Don't forget to block the back of the head which should not be needed. Again , this is if you are fitting a one way check valve to the crankcase vent for the partial vacuum effect.
 
As per an earlier post. I had a major problem with oil overflowing the catch bottle. I removed the oil air separator and put the breathing back to the original Norton specifications. I added a breather hose to the oil filler neck with a one way valve and put a small catch bottle behind the headlight bracket. First real big test was ride to Phillip Island GP last year round trip 2000 km with hard riding mountain roads 100 mile an hour at times. Very little oil used and about 10mls in catch bottle.
With a breather hose on the oil filler neck you can feel the pressure pulsing even at idle.
 
TonyA said:
Remember that the frame oil tank must vent also. If I was putting in the one way valve , I would look into routing the frame tank vent to a filter. Or if you are already doing the IAC blocking then route the frame breather to the now unused IAC to air box fitting . Old Nortons have a separate oil tank vent lets not forget that. Now the only oil coming out of the frame oil tank vent will be when overfilled or super downhill and braking. Then I would still run a catch bottle just in case you get oil in the airbox. Don't forget to block the back of the head which should not be needed. Again , this is if you are fitting a one way check valve to the crankcase vent for the partial vacuum effect.
Click to expand...

The current Norton setup has the breather pipe from the oil tank going into the head, but also has the rocker cover breather hoses blocked off (new bikes no longer have the banjo bolts). So there really isn't any breathing going on. The only breathing is directly from the crankcase to the airbox via the separator.

Good to hear nopdog. Validates your approach!
 
The vent path on banjo-less rocker is through push rod tunnels , through push rod tunnel drains , through cam cavity , through cam cavity drain hole , through timing side , and finally back to crankcase and out the breather . I am just reminding folks to be sure they still have a vent for their oil tank. There may be enough venting for the oil tank with the one way check valve in , But I am not certain of that. I suppose that can be tested for to make sure oil comes out freely and goes back in freely at all operation conditions - high speeds etc.
 
Yes, you're correct of course. My use of a one way valve will not effect the engines breathing in anyway. It's only there to prevent the engine trying to breath through the drain hole in my oil separator.
 
Last edited:
Ok i'm onto this !!

Now just need to miniaturize things :cool:

Unraveling the 961 part two (oil in the air box)
 
Suppose I should do an update on this thread now it's popped back to the top again. Turned out I didn't really need to try and get clever with one way valves etc. The little air/oil separator I installed is doing a great job. It seems to catch mostly water vapour with just enough oil to turn it cloudy.

Bike looks a lot cleaner without the ugly Norton air/oil separator, catch bottle and associated tubes, engine is no doubt happier not ingesting oil.

Unraveling the 961 part two (oil in the air box)

Unraveling the 961 part two (oil in the air box)
 
Found the oil/moisture filter out of the states,

https://www.ebay.com.au/itm/New-1-4...Can-Black-Baffle-For-Honda-Civic/312222441040

Just wondering, the crank breather is also to "burn" nasty's that are created in the internal engine that vent, seeing that your trapping oil/moisture is it not best to feed the exhaust back into the airbox ?? I understand that may pose a dilemma in that this exercise was to rid the intake of oil (we have done that) so to round it off pipe it back.

To add to this, where does all the positive pressure come from, if the vent is pumping this out surely its not all leakage past the rings ? there needs to be an "Inlet"
 
Question ???

Whats the consensus on the point of the breather from the head to the tank ??

Pressurize the oil system in some way, pressure equalization ??

As the Oil Reservoir does not have a subsequent path to atmosphere and obviously if you allow the head/crank will expel via this path if you loosen the oil cap, whats the point ??

I think its to allow for a non atmosphere pressure equalization back and forth from the oil system.

Thoughts ?
 
Breather - Just a tank vent, can't go to atmosphere or all the icebergs will melt tomorrow.
Positive pressure - leakage past the rings seems to be the answer.
I can't remember which thread it is in but i tried a reed valve in the crank breather line. It calmed down the chuffing in the oil tank but did nothing for oil in the airbox. That was in an early system, no inline filter or non return valve etc.
I've just received the factory oil system upgrade kit with non return valves etc, will be a month or two before i get to fit it. Not yet sure whether i will fit the full factory system or do a hybrid like iwilson's.
 
Bluey72e said:
Whats the consensus on the point of the breather from the head to the tank ??
Click to expand...

This vent allows the free flow of oil into and out of the oil tank and to mitigate any pressure or vacuum build up as you have stated. I would not block this vent .
 
That sounds great, your efforts in support of these bikes are hugely valuable to us mere mortals.
 
TonyA said:
This vent allows the free flow of oil into and out of the oil tank and to mitigate any pressure or vacuum build up as you have stated. I would not block this vent .
Click to expand...

Thanks, hadn't planned on blocking the vent just trying to understand the concepts surrounding the design etc but have been reading all the threads and even pulled my oil system apart to check on a few of your pointers in regards too swarf in the non return valves.

All this was kicked off when for no apparent reason mine blew a dinner plate sized pool onto the floor randomly via the airbox/collector bottle.

My hypothesis is that the factory non return valves stuck open randomly and flooded the sump, on starting bike that blew excess up and overcame the capabilities of the air/oil trap and eventuated in the mess on the floor.

All my non-return valves were clear and indeed the reservoir did not drain via the oil cooler just dripped a bit initially so proved the valve worked.

I'm actually of the opinion that if the vent had been as JWilsons is now and the engines were originally designed with the vent via the rocker cover, that oil would have just dropped into the engine as impossible for that glut of oil to traverse the space and out the vent on opposing side.

I have reed valves, oil separators and pipe..... I will await Mr Richard-7's knowledge transfer before doing anything further though.
 
I didn't want to take this too far . But if you would like to tell us again what your bike has on it ? What year etc.. So you have the 1 way valve in the oil pump and in the return line . Also you have the black in-line filter screen that will stop debris from clogging the oil pump one way valve . Also , have you monitored your oil tank level while parked for say a week or more without running the bike ? When everything is in order the level should stay constant in the oil tank , not slowly dropping into the sump from either feed side or return side . Whatever new breather system you decide on , old Norton way , new Norton way , iwilson way , Richard-7 way ... It helps the engine to stop the wetsumping if you have any ! So what I am saying in short is the Norton Factory fixes for wetsumping do work very well if all the parts are functioning ..
 
Thanks TonyA

I have all the standard 2015 factory anti wetsump and anti oil/airbox breather mods, only thing is no "filter" on the return line.

As mentioned I believe that all's generally well but there was a "glitch" that caused the glut of oil to pass right through the oil/aif trap.

Am currently diligently monitoring the level both before and after running and again all seems correct. I am of the opinion that JWilsons modifications or rather reversion to the breather via the rocker cover would of actually saved me the flood of oil I experienced.

That's all folks..!! no need to delve deeper as I know from the historical post this is just churning over well covered ground for you all.

Thanks
 
You must log in or register to reply here.
Back
Top