Engine Crankcase Breather

I have collection boxes on my Hondas and that moisture/oil that is collected in them is diddly squat. It takes a long time to amount to much. I really see no reason for the collection box other than less chance of dirt being sucked into the engine, but it's still not a closed system.

So, is the way to do this without a collection box to place a filter on the hoses/hose and clean or replace the filters as needed?

Frustration here, because so many of you are using Uni filters and there does not seem to be an agreeable way to address these breather tubes !!!

Seems to me that the mention of Uni filters should lead to describing what was done with the breather tubes in almost the same sentence on this forum, but that doesn't happen. Thread after thread seems to go this way.

Scott
 
figure8 said:
I thought it was common knowledge that these bikes came lean from the factory. When I put Uni's and rejetted my carbs my bike ran better than ever.
Click to expand...
That common knowledge only refers to the 1980 to 1983 (1984), that used BS34 carbs. The 1970 to 1979 with BS38 carbs are not lean from the factory. Yes, your engine may have run better because you had BS34 carbs that were too lean, and you improved that by increasing the jet size.
There is no evidence that UNI filters improve the engine operation as compared to stock air boxes.
 
If you Google search "breather pipes" the first article to come up is from Wikipedia. It traces the history of these breather systems. With a breather pipe open to the environment this accounted for approximately half the hydrocarbon emissions from a car. These HC emissions were linked to smog formation so the move was to dispose of these HC emissions by venting them to the carburetor and burning them.

On the XS the breather is baffled so there isn't free movement of air in and out of the crankcase due to this resistance. Would be interesting to know the volume involved wouldn't it? Must be small because I do not see any oil coming out - must go blow up it to see if it is blocked!
 
mrtwowheel said:
Seems to me that the mention of Uni filters should lead to describing what was done with the breather tubes in almost the same sentence on this forum, but that doesn't happen. Thread after thread seems to go this way.

Scott
Click to expand...

I've three bikes here all with Uni's, all with single breather outlets and all with the power brake booster valve. Power brake valve is directed over a Uni, pick whichever. If it bothered me that one pod may be getting a tad more oil than the other then I'd redirect to the other one or find dual outlet breathers and mount two valves.....but it doesn't and I don't. The grizzled one with the Krankvent setup may be the ultimate but until this fails, it's my fix.
Other opinions may vary.........
 
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The baffle in the breather system is a labyrinth type. It has a couple of 180 degree turns, which allow the air to move in and out freely, but any oil droplets have too much mass to make the quick turns, and thus the oil drops down and returns to the sump.
 
I just checked and there was only a dribble of oil in the tubes directly below their entry into the carburetor. I blocked one tube and blew up the other and there was very little resistance through the baffles (At the speed the air will pulse when the engine is running the resistance to flow will increase a lot). When I released the tube all the air came flowing out at a steady speed, not one big rush, which suggests the baffles are doing their job. I repeated with the dipstick (not me!) removed and the air just blew in and out the engine.

Conclusion: My system seems fine, but didn't taste that great.
 
Thanks RTG. A labyrinth type baffle, seems a bit like centrifugal separation. Those engineers really knew what they were about! The proof is in how well it works.
 
nj1639 said:
I've three bikes here all with Uni's, all with single breather outlets and all with the power brake booster valve. Power brake valve is directed over a Uni, pick whichever. If it bothered me that one pod may be getting a tad more oil than the other then I'd redirect to the other one or find dual outlet breathers and mount two valves.....but it doesn't and I don't. The grizzled one with the reed setup may be the ultimate but until this fails, it's my fix.
Other opinions may vary.........
Click to expand...

Is it possible to use this power brake valve with a twin breather outlet?
 
retiredgentleman said:
That common knowledge only refers to the 1980 to 1983 (1984), that used BS34 carbs. The 1970 to 1979 with BS38 carbs are not lean from the factory. Yes, your engine may have run better because you had BS34 carbs that were too lean, and you improved that by increasing the jet size.
There is no evidence that UNI filters improve the engine operation as compared to stock air boxes.
Click to expand...
Noted
 
Correction, nj; Mike's XS sells a reed valve. I use a Krankvent unit, which is not a reed valve; for details on it, visit the site. You won't be seeing an oil mess on your Uni filter because your one-way valve is keeping air from entering the crankcase, so that there's little air to be pressurized and carry oil out with it when the pistons fall.

Re. the virtues of one-way valves, it took a long chat with MMM for me to get the ideas involved through my thick skull, so I don't fault anyone for not seeing the need right away. Bottom line: if you try it, you'll like it. Peace.
 
Once again, This thread has turned into a lecture about the necessity of crankcase ventilation and the function of the stock air box.

The question is WHAT TO DO ABOUT BREATHER TUBES WHEN USING PODS.
 
I have seen pictures showing where people use the single breather line and just run it into a neat little pot to catch the oil. When the pot fills up they empty it. I did see a nice little Stainless pot in one photo strapped to the frame by the engine mounts. I cannot remember where I saw them but it was an XS site.

Edit: Here is an Ebay link of the sort of thing:
http://www.ebay.ie/itm/JAPSPEED-UNI...730864?hash=item256dc9c9b0:g:EqgAAOSwPe1T22DA

Some have an oil filter outlet.
 
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I run one of Mikes crankcase vents on my 650, seems to work as required and no problems. But it is an odd design and difficult to find a location to mount it. But my bike is modified a little so that wasn't a problem for me. Before the vent I just ran the two outlets down the back of the engine, and through two small filters. I would get a little oil / water drops after a hard ride, not much to bother about. My engine is completely oil tight. Griz's crankvent is probley the best solution, next to stock airboxes, but that's not what you want? Just run the two hoses and filters, good enough.
 
Paul75 said:
Is it possible to use this power brake valve with a twin breather outlet?
Click to expand...

Yes, Paul.
The stock hoses are the perfect diameter for the end of the valve that goes toward the engine side and the valve has a 90 degree turn to it, so I can imagine positioning 2 power brake booster valves directly on or imbedded into the Uni's with a little ingenuity.
Now I'm thinking of that spare dual output breather that I have......that's my English need for symmetry bubbling up in my DNA.....lol
Grizzled one, correction duly noted!
 
I think a brake booster valve is actually a check valve which allows air [vacuum] to be pulled thru it but won't allow air to blow thru. The reason you still have power brakes when your engine quits. mine is going to be a very low miles bike so I'm just going to run the hoses out the back of the engine.
 
Paul75 said:
Bob, if there is already a check valve in the breather arrangement why do people bolt on brake check valves?
Click to expand...
I don't know ! perhaps the earlier modles didn't have the checkvalve .... take the breather hose bracket off and look and see if it's just a hole or a reed valve .... or perhaps READ the manual if you can find one that shows the breather unit in detail.
my 83' has the Reed valve and it is a good thing to have as Griz said...because it keeps the engine running in a slight vaccuum....good for seals and stopping oil leaks.....
....(well, i think it does ...maybe NOT)
Bob......
 
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Paul, there is no check valve in the OE crankcase breather on any XS650 motor. None. Zero. Zip. Nada.That notion could only be entertained by someone who has never taken an XS650 motor apart or doesn't understand what he's looking at. Peace.
 
LOL OK Grizld1.... Finish your statement ! which direction should the check valve be IN ???? allow air out and not in or allow air in and not out ?????
the answer is obvious to you and I but to prevent seal leaks I think we should tell them to put the checkvalve in so the air can go out and not IN.....
....hehehhehehe ! .... who would'a thought the breather would be so difficult ?
.....
Bob......
OK I admit ...I could be WRONG ....again I thought my breather had a reed valve in it
but it may not.... Listen to the man that knows ...in that case a check valve is a fantastic thing to add to let AIR OUT and not IN !
 

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