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

Browsing this thread I couldn't determine which Yamaha this valve came from, probably because I'm thick. Could someone please enlighten me?
 
Browsing this thread I couldn't determine which Yamaha this valve came from, probably because I'm thick. Could someone please enlighten me?
It doesn't come from a Yamaha but from a Chinese moped or small engine and then repurposed by MikesXS to fit an XS650. You will never find one on any Yamaha leaving the factory so searching for it by Yamaha will always go back to MikeXS.

To find a similar valve go to ebay and search for 'Motorcycle EGR valve' and pick one out by picture.

An example

Motorcycle Exhaust Emission Valve (EGR Valve) for Kinroad, Skyteam (EGR006)

 
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This is a great thread and I have a question.

I have a reed valve on the engine vapour vent line up near where it enters my oil tank. The reed valve is working properly.
In addition, I have a Feker anti oil sumping valve that I manually turn on and off. (So there is no excess oil in the sump possibly being blown onto the engine vent line when the engine is started)

Way back in this thread there is a fellow who has a reed valve and vents the output into a bottle.

I can't do that on my 1973 850 as the output of the reed valve (when I look into oil tank with engine running)
spits oil into the tan along with the fumes. I think if I vented that line into a catch bottle, the bottle would rapidly fill
with oil and eventually overflow and I would lose all the engine oil.

Do I have a problem at this time? Yes, I am getting water in my engine oil and I think that I need to ge on longer rides
to stop it happening as blowby is obviously condensing. But another solution I could add on top of longer rides is to
either increase the velocity of the vapours after they enter the oil tank (by raising the level of the oil) or possibly venting the engine vapours via reed valve to atmosphere and catch bottle.

Thanks and I look forward to your thoughts

Dennis
1973 850
 
I would be looking inside the timing case if my 850 breather was spitting oil. The 850 has the steel pipe running out the back of the timing cover where the failed starter motor was supposed to go which is high up. Sounds like the oil level is getting too high inside the timing cover maybe from a blocked drain hole.

Pic of inside the timing side 850 off Atlantic Green

 
I would be looking inside the timing case if my 850 breather was spitting oil. The 850 has the steel pipe running out the back of the timing cover where the failed starter motor was supposed to go which is high up. Sounds like the oil level is getting too high inside the timing cover maybe from a blocked drain hole.

Pic of inside the timing side 850 off Atlantic Green

Thanks Kommando
I didn't know that oil through the engine breather was not normal. I thought that the timing chain would be splashing oil everywhere including on the entrance to the engine breather.

I have had timing cover off, but obviously no further as my bike is running.
Is there an oil return hole, into the crankcase, that is a possible clog because whoever rebuilt the engine used gasket sealant and plugged it up? Might you be able to point that out to me with an arrow?
Thanks
Dennis
 
Try reading this thread which also includes adding a lower drain hole as the tilting forward of the Commando engine fills the timing side chamber with oil.

 
This is a great thread and I have a question.

I have a reed valve on the engine vapour vent line up near where it enters my oil tank. The reed valve is working properly.
In addition, I have a Feker anti oil sumping valve that I manually turn on and off. (So there is no excess oil in the sump possibly being blown onto the engine vent line when the engine is started)

Way back in this thread there is a fellow who has a reed valve and vents the output into a bottle.

I can't do that on my 1973 850 as the output of the reed valve (when I look into oil tank with engine running)
spits oil into the tan along with the fumes. I think if I vented that line into a catch bottle, the bottle would rapidly fill
with oil and eventually overflow and I would lose all the engine oil.

Do I have a problem at this time? Yes, I am getting water in my engine oil and I think that I need to ge on longer rides
to stop it happening as blowby is obviously condensing. But another solution I could add on top of longer rides is to
either increase the velocity of the vapours after they enter the oil tank (by raising the level of the oil) or possibly venting the engine vapours via reed valve to atmosphere and catch bottle.

Thanks and I look forward to your thoughts

Dennis
1973 850
Sounds to me likes some confusion. The engine breather goes to the pipe that connects to the neck where you fill the oil. An EGR or especially a reed valve will normally have some oil entering the tank there and that hose must not connect to a catch bottle. The tank vent which is closer to the front of the oil tank normally vents to the air cleaner but many have that line to a catch bottle or small filter. That should never have oil in it if the tank is properly filled - halfway between L and H with the engine fully warmed up and shut off.

If your hoses are connected correctly then I think you are over-thinking and need to go for a ride.
 
Your rational?
I recall that comnoz did some very extensive testing when developing his reed valve, and he found that placing it as close as possible to the crankcase gave far better results than hanging it on the end of a hose from the timing chest breather.
I did a compromise by drilling and tapping the rear crankcase wall for a hose barb, which connects to my reed valve via a short length of hose´, and then dumps the oil back into the tank.
I did this simply to avoid having to machine a flat surface on the rear of the crankcases. If I was doing it again, I would simply buy the valve from NYC Norton (or use Jim Schmidt's version) and save me a lot of buggering about.
My solution does work quite well though, apart from making me worry about the hose connections - if they were to fail, I would definitely notice the oil getting dumped onto the rear tyre!
 
You will never find one on any Yamaha leaving the factory

Further research suggests that the Yamaha Zuma 50 has a rather neat reed valve setup. Unfortunately, not sold in this country. I'm currently waiting on one from an Aprilia RS125.
I can't believe that I have only recently stumbled on this concept, and lots of people have been using them for YEARS. My Bonneville occasionally has a little weep around the head, the legacy of a hurried top end assembly 40 years ago, so I'm looking forward to trying a valve on an additional breather in the TDC tool hole.
 
Further research suggests that the Yamaha Zuma 50 has a rather neat reed valve setup. Unfortunately, not sold in this country. I'm currently waiting on one from an Aprilia RS125.
I can't believe that I have only recently stumbled on this concept, and lots of people have been using them for YEARS. My Bonneville occasionally has a little weep around the head, the legacy of a hurried top end assembly 40 years ago, so I'm looking forward to trying a valve on an additional breather in the TDC tool hole.
Nice inline version are the Benelli BN125, Yamaha YBR125 or YZF125 EGR valves

Here’s a couple of examples




If you don’t need the mounting lugs you can just cut them off and make it even neater.
 
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Further research suggests that the Yamaha Zuma 50 has a rather neat reed valve setup. Unfortunately, not sold in this country. I'm currently waiting on one from an Aprilia RS125.
I can't believe that I have only recently stumbled on this concept, and lots of people have been using them for YEARS. My Bonneville occasionally has a little weep around the head, the legacy of a hurried top end assembly 40 years ago, so I'm looking forward to trying a valve on an additional breather in the TDC tool hole.
Putting a breather in the TDC hole and via a reed valve works well, well it does for me at least. Don’t do it as an additional breather though coz it will still blow out / suck in and bypass the reed valve.

If your Triumph breathes through the primary case, simply putting a reed valve on the outlet of that seems to work well enough.

No guarantee it’ll clear up your leaks though… it is a Triumph after all !
 
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Home made Sump valve
Yamaha EGR Reed Valve Breather Hack '74 MK II Completed (almost)
Yamaha EGR Reed Valve Breather Hack '74 MK II Completed (almost)
 
Home made Sump valve
Yamaha EGR Reed Valve Breather Hack '74 MK II Completed (almost)
Yamaha EGR Reed Valve Breather Hack '74 MK II Completed (almost)
Nice Job!!, One, question though - As You don't have the vent pipe protruding higher than the filter gauze, how does that effect the scavenge side of the oil pump? The Comnoz / NYC version protrudes about 50mm above I think, so so it's only pushing the initial wet sumped oil, and once that is cleared the pump takes over. I'm curious, as I made something similar, (with Jim's permission) but took a lot of time to extend the pipe the right amount so it cleared the inner baffle. This was the initial version, but it was subsequently extended....


1735756146103.png
 
Nice Job!!, One, question though - As You don't have the vent pipe protruding higher than the filter gauze, how does that effect the scavenge side of the oil pump? The Comnoz / NYC version protrudes about 50mm above I think, so so it's only pushing the initial wet sumped oil, and once that is cleared the pump takes over. I'm curious, as I made something similar, (with Jim's permission) but took a lot of time to extend the pipe the right amount so it cleared the inner baffle. This was the initial version, but it was subsequently extended....


View attachment 117910
That photo was taken of my first attempt a few years ago just to make suer everything would work and I hadn't researched it very well and wasn't aware of the need to be protruding that much. Later I did extend it to about 25 mm. Can't remember if I used a 7,62 x 54 Russian or Brit 303 shell case, had to notch out a socket to tighten and remove it. I did it this way for more ground clearance and it was cheap and easy. If anyone wants to try it make suer you mark whare you want the nipple to point on the plug before removing .
 
I had quite a hunt for suitable reed valves, and the following might be of use to someone looking for one.
I got hold of a reed valve for the Secondary Air Injection on an Aprilia RS125. It has an interesting circular reed valve, but when I blew through it there was a loud warbling sound, which I didn't want to have emanating from my motor. I then bought an SAS valve for a Vespa. This has a quieter rectangular reed valve and a vacuum connection for a diaphragm. The diaphragm shuts off the breather when vacuum is applied, so the valve can be used as is with no vacuum pipe as no shutoff is required.
I fitted the valve via the TDC hole on my Triumph, as a totally different breather additional to the existing timed breather (despite Fast Eddie's advice above). Given time I may block off the timed breather, but in the meantime there is a perceptible airflow out of the new breather pipe.
 
Forgot to mention:
Exhaust air injection systems are often described as:
SAS
AIS
ASV
Secondary Air Valve
Air Injection check Valve
and (incorrectly) EGR

These valves are used in a pollution reduction scheme where fresh air is introduced into the exhaust in order to assist completion of combustion. This is regarded as secondary combustion, hence the name Secondary Air Valve. This introduced air reduces CO gas in the exhaust and assists the operation of the catalytic converter by maintaining the temperature of the gases entering it.

More importantly, they can be used to assist incontinent old motorcycles.
 
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