Yamaha EGR Reed Valve Breather Hack '74 MK II Completed (almost)

olympus said:
It may be the camera angle but in the first pic it looks like the breather hose from the timing chest is siting on the engine cradle (causing it the arch slightly downwards) & the PCV is below the level of the outlet hole in the timing chest ... this surely cant be right as the valve will fill with oil & not work correctly????
As i said it say be the camera angle of my eyeso_O;)
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Reed valves work very well in oil. Maybe better than not as it keeps them gunge free. As demonstrated by the NYC / Comnoz sump plug version.
 
olympus said:
It may be the camera angle but in the first pic it looks like the breather hose from the timing chest is siting on the engine cradle (causing it the arch slightly downwards) & the PCV is below the level of the outlet hole in the timing chest ... this surely cant be right as the valve will fill with oil & not work correctly????
As i said it say be the camera angle of my eyeso_O;)
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No it works well and has been on in that position for over 10 years now, no oil and don't get any oil in the catch bottle, it only gets a small dribble of oil in the catch bottle over a 1 year or more, its a clear catch bottle and would see if it had oil in it.
 
Mart UK said:
On a mk3 the starter motor is in the way. I couldn't fit it down there.
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Same is true for the cNw starter. In fact, cNw supplies a shorter spigot and a right angle hose to allow getting at the breather connection and routing it away from the starter motor. I had to run the hose up behind the air filter plate and install the valve even with the oil tank. Fits OK, and as long as I get no oil leaks I assume that the valve is working.
 
As Rob SS points out , close as possible to the source of the pressure. A mate fitted a similar PCV to his 650 Triumph and it was mounted towards the end of the long breather hose that Triumph routed along the LHS of the rear mudguard, all it did was act asa siphon and pulled more oil out of the crankcase than normal.
I run the sump reed Vv breather in all three of my Nortons and they work a treat .
Regards Mike
 
There are other options..

Installed CNW Comstock reed valve breather off timing chest

I installed a CNW/Comstock reed valve breather on my P11 timing chest in place of my hack job PCV breather. I'm hoping the CNW reed valve breather works better somewhere in the power delivery. First and foremost the CNW reed valve breather is not designed to be installed off the timing chest...
www.accessnorton.com www.accessnorton.com
 
Yamaha EGR Reed Valve Breather Hack '74 MK II Completed (almost)
where is the nearest bank
 
I think the mayonnaise issue depends also on climate and if you do long journeys or short
I have a Yamaha egr valve bolted on the back of the timing cover on the blanking plate on my 750
I get zero mayonnaise from that setup
 
Very happy to have the yamaha reed valve under the petrol tank, no leeks from head nor cranckcase.

It doesn't have the oil clearance functionality of the CNW or the NYC reed at the bottom of the cases as caches from the upper part of the timing cover and for this reason i fited a tap to the oil line to avoid wet sumping.

If i was to do it again i would probably go for the NYC and dismantle the oil tap to avoid sizing my motor if I ever forget to open the oil tap, but that is another story.
 
Regarding valve placement, like others have stated running it off timing chest breather to oil tank does seem to work well enough. I check mine periodically with oil filler cap removed, placing a finger over the pipe connection at filler neck just as engine starts up. You can easily feel the pressure pulses from it. And I've zero leaks from engine past few seasons now so it's a good-un!
 
cash said:
Fitted lower down with a short pipe could cause oil to pool up in the valve. Just a thought.
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Don’t think it matters. The sump type sit in oil all the time and work jus’ fine.

May even be a benefit, keep it lubed and prevent emulsified condensate issues.
 
About the emulsified condensation locking the valve, I don't think that could be so strong to hold the motor internal pressure, as is enormous, imagine how difficult must to go throug a join judt by blowing!.

I have put my finger in the breathing tube at the oil tank and works so well you can't feel the breathing, this little petal valve is just great!
 
Dan1950 said:
This looks like it grew there. Just cut, trimmed the hose and it tucks right in ahead and above the battery. All I need to do is cable tie it to the top tube and add some hose clamps.

View attachment 92791

View attachment 92792

View attachment 92793

Less than $50.
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Dan, That's where I put mine. The mayonaise can drain both back to the crankcase, and to the tank.
The air volume in the 1/2" hose poses no lost effect of reed valve action. 45 years of engine breathers experience.
I stand with your logic Dan, and proved it with 40,000 miles that way.
 
NorCat said:
About the emulsified condensation locking the valve, I don't think that could be so strong to hold the motor internal pressure, as is enormous, imagine how difficult must to go throug a join judt by blowing!.

I have put my finger in the breathing tube at the oil tank and works so well you can't feel the breathing, this little petal valve is just great!
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Holding it open is NOT fighting against the ‘enormous‘ engine pressure, just the reed spring pressure.

Its not really the emulsion that does this, it’s the fact that the emulsion causes things to corrode, then the valve can’t work correctly.
 
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cash said:
Probably returns the sump oil better than the oil pump too.
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There’s no doubt about that.

I tested it once… I forgot to drain the sump after sitting for a LONG time. I know that the sump would have been full and the tank uncomfortably empty.

But I forgot (I’d been using my Triumphs which don’t sump) and pressed the button on the cNw e start and it fired up perfectly normally.

After a few seconds I realised I’d forgotten to drain the sump, and noting that nothing untoward had happened, looked in the oil tank to find all as normal.

I’m not saying this should be the SOP, I still believe it’s sensible to drain the sump after a long sit, to protect the drive side oil seal if nothing else, but it did prove the effectiveness of the sump breather at returning the sump oil.
 
Fast Eddie said:
There’s no doubt about that.

I tested it once… I forgot to drain the sump after sitting for a LONG time. I know that the sump would have been full and the tank uncomfortably empty.

But I forgot (I’d been using my Triumphs which don’t sump) and pressed the button on the cNw e start and it fired up perfectly normally.

After a few seconds I realised I’d forgotten to drain the sump, and noting that nothing untoward had happened, looked in the oil tank to find all as normal.

I’m not saying this should be the SOP, I still believe it’s sensible to drain the sump after a long sit, to protect the drive side oil seal if nothing else, but it did prove the effectiveness of the sump breather at returning the sump oil.
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I've done exactly the same
No issues
 
Speaking of mayonnaise...I only seem make a little bit when its raining and cold which gets discharged via a second breather on top of the oil tank down onto the road...its shit on salad 🥗
 

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KiwiShane said:
Speaking of mayonnaise...I only seem make a little bit when its raining and cold which gets discharged via a second breather on top of the oil tank down onto the road...its shit on salad 🥗
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Shane,
I keep looking at the vent on your right side cover and would like to know what you used to cut that out so nicely and how you attached the screen.
Thanks,
Mike
 
YING said:
Shane,
I keep looking at the vent on your right side cover and would like to know what you used to cut that out so nicely and how you attached the screen.
Thanks,
Mike
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I drilled 2 holes and cut it out with a cheap had held jig saw with steel blade and set the mesh in with a marine adhesive sealant...after I painted it.
Done the same to vent my primary both ends with drain holes bottom of inner primary ...a wise man said to me (that we know)...its far better than the swiss cheese look...🙂...im sure its not everyone's cup of tea but to me its all the ventilation needed for a road bike if any....
 

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