I have had a problem with oil emulsifying in the breather hose and partially blocking the hose. I did have a reed valve in line but that was getting clogged with oil as well. I have disconnected the breather hose and it now points to the road and the engine breathes much easier but this a obviously is not a long term solution any ideas?
How much oil should come out of the breather?
- Thread starter Paul1972
- Start date
- Status
DogT
VIP MEMBER
- Joined
- Jan 20, 2009
- Messages
- 7,393
When I asked Mick Hemmings how I should let my un-modified '69 breathe, he suggested dumping in in the air without a valve or anything, so if you get a lot of oil coming out, you might try that. I know it's not the best, but it keeps it off the bike if you can route it down and out. You may also try not filling the tank so much, running it more towards the L mark.
Dave
69S
Dave
69S
- Joined
- Apr 15, 2009
- Messages
- 11,540
How many of you with the reed valve breather (especially on a 72) put a drain hole in?
xs650-breather-exposed-t7345.html
- Joined
- Jan 23, 2011
- Messages
- 263
I just put mine up under the seat of my 72, at an angle where gravity drains it into the tank. No hole needed.
- Joined
- Jan 31, 2010
- Messages
- 3,148
There is no need to worry about it. "Raw" oil in the breather hose will occur if the sump is overfull due to wetsumping on startup. After a short period it will quit. It's not an issue at all if the breather is routed back to the oil tank (per oem) or to a catch can. Whether there is a valve present doesn't matter and the oil in the valve has no effect on crankcase breathing; the valve will still open/close normally. If routed directly to the air, you could dump a bit of oil wherever the hose terminates. My bike did that if left for more than maybe 2 weeks without running and it's one reason I changed from "open air" and re-plumbed it back to the oil tank - to avoid those puddles.
- Joined
- Oct 19, 2005
- Messages
- 18,978
Having had this messy excretion on first getting my Combat, which had been over filled by owner forgetting to un-wet sump it prior to determining need of oil, took 1000 miles or more before the thing got to its proper oil level, about 1/2" Below the 750's dipstick reach. Same thing with primary for me to learn, then gear box too. By no longer over filling as manual or inspection plugs would tempt, it didn't white foam or make exhales or excreted mess. I vote with the oil fill suggestion.
I took a 40 mile ride yesterday on a fresh oil change. When I got home and starting checking the bike over clear condensation was dripping out of my dangling breather hose. There was some air bubbles in the oil tank and the oil level was between the lines. I have a clear hose on my MK III and you don't want to stand directly behind the bike upon start up. The white milky mess will soil your booties. :lol:
Tim_S
Tim_S
Thanks for the help guys, I will try and put a drain hole in my xs650 reed valve but it's good to know its okay to route to open air. I had noticed if I fill the oil anything past the L on the dip stick it tries to escape from everywhere on a fast run (ish), I had thought it was just my bike.
Paul
Paul
- Joined
- Nov 10, 2006
- Messages
- 1,540
swooshdave said:
How many of you with the reed valve breather (especially on a 72) put a drain hole in?
xs650-breather-exposed-t7345.html
Dave,
Surely the drain hole will reduce the effeciency of the valve ? Having said that perhaps it is something I should do to mine to prevent the built up of oil in the timing chest. But then again since removing it completely I haven't noticed any real change 'cept the oil return is now predictable.
Cash,
A breather valve nut since 1967
- Joined
- Apr 15, 2009
- Messages
- 11,540
cash said:
Heh, it's a small hole. Comstock explained it better in one thread, but I can't remember where. Obviously the drain hole will have no effect when the reed valve is open. And it's small enough that when the valve is closed (on "vacuum") that nothing can really get through. Remember also that the reed valve works on rapid pulses and the small hole just can't pass anything fast enough. But let's say there is a bit of oil up above the valve and the engine is shut off, then it is big enough to slowly drain back to the crankcase, when speed isn't a concern.
Putting the valve up high would reduce the need for a drain, but the valve is more efficient the closer to the crankcase.
I'll know more the more the bike gets run, but the last time it seemed to work as advertised.
Paul1972 said:
Being a 74 850 I would think that very little oil should pass. I believe Cash is on track. These bikes warm up fairly quickly but, however, the oil does not. I can take 20 to 30 minute of riding for the oil to get hot. If it doesn't (due to short hops) condensation will form. The oil infused water becomes air born and that is what is bypassing.
There are so many people with 750's that have breather issues that they are jaded by the subject. Your machine should not have a breather issue and, although they may be only very slightly helpful on 850's, a reed/breather check valve can also be bad as you have discovered.
I would reroute the line as intended and get that thing good and hot once in a while. The moisture will leave by being evaporated. If you keep your line pointing to the ground and you get it good and hot, after a while you will only see water spots on the pavement rather than that nasty stuff.
As far as breathers go, I run 2. One off the mag boss and one off the lower crank, both with reed. If I am going to run a reed (restrictive IMHO) then I better run two. I hear them sing in harmony when I crank the motor over. Notice the good stout line running to the xs650 reed.
For clarification, oil in the timing case will only get so high and dump to the sump through this hole and returned to the system.
Paul1972 said:
the amount of oil is a way of saying how much blow by you have on your bores
When you have the opportunity look at your pistons to see for blow by
If air (pressure ) is getting past your pistonrings then you get pressure in your cases wich wil blow oil out of your breather (logic isn't it )
You can fit 20 breathers into your system but it will not change the health of your engine
the size of the breatherline however matters, it is not a good idea to use small diameter hoses out of the cases , you better run a bigger dia witch you can then reduce further down the way
however too much oil coming out of your breather is bad news so it is better to look where it is coming from(in the engine) then to see how to to cure its symptoms (reed valve)A commando in good health can benefit from those valves but does not NEED it
- Status
