Crankcase breather

[Tim of DO THE TON]

First thing I did was find a single spigot breather and modified it to breathe better (there's a documented mod out there somewhere). Then I ran a single tube to a catch can mounted under my seat, which now has a UNI clamp on filter on it.

I used the tubing you can buy from MikesXS for this purpose. Thin walled - which does mean it's prone to kinking but I'm running a short length with no real bends.

Apologies for the crappy cellphone pics.

 

[bt24]

Bryan,
Do you have a catch bottle on the other end of that tube?
I'm using a cheap auto parts store PCV valve and it still mists some oil. it's not pointing at my swingarm, so it just makes a little mess. Not too big a deal, but not much better than the no-valve setup I had before.
Thanks,
Tony

Tony,
no I dont use a catch can, if there is any oil mist it just goes on the dirt, but if I was going to be riding on the street I would have a catch can for sure. To this day I have not really had any oil mist blow by, so I guess thats good.

B

 

[pcoumbe]

Dual outlet breather box converted to a single. thin walled crankcase vent hose from MikesXS with two light external springs and a billet filter mounted to the crankcase. Easy to remove the foam from the filter and wash at service times. Hasn't left a spot of oil on the ground in over 3000klm.

 

[TurboFarviknugn]

What would cause MORE oil to come out of the vent hose WITH the power break valve dealio on there ? I had one that lasted about 9-11 months started seeing more oil I checked the valve it was shot, installed another much better but still getting more than I would like. Thinking of making a catch can, but that would just contain the mess not fix it. Could worn rings or valve giudes cause this ? Bike runs AWSOME 75 mph 22 miles each way to work and back home every day, no problems, just this annoying oily mess. SOOOoooo bad want to do a NEW RE-PHASE but gotta wait until this SEQUESTOR crap is over to have any play money again.

 

[TurboFarviknugn]

OOPS I forgot to add the picture this is typical after a ride to work or home.


And yes I have LOWERED the oil level I check it daily and keep it where it just touches the bottom of the dipstick when sitting full upright in level ground.

 

[jd750ace]

On Road Stars, we run the hose up-hill along the backbone and install a PCV valve. I forget the part number, but you just turn it up. The oil that does go up the line ends up just running right back down into the case. Road Stars also make a mess if they are run down low, and don't care too much about how perfect your oil level is. Could be a Yamaha air-cooled motor thing? Who knows. I'm thinking if I have room up the back bone to cap one and plumb the other on mine. I read this article today and I'm wondering if changing the size of the return hole in the baffle will help reduce the mess. I'll get into that after I finish getting it running!

http://www.650motorcycles.com/XSbreather.html

 

[TurboFarviknugn]

THAT was an interesing read, THANKS FOR THAT. might just try that, or hummmmmmm any one got an early style breather they want to let go of, cheap ?

 

[pcoumbe]

I was going to mention the oil level but you've already addressed that so I don't really know what else to advise except to check your breather box against the parts and service manual reference pictures to be sure all of the baffle plates are included and up the right way to allow them to separate the oil as they're supposed to.
I have a new big fin barrel and piston kit fitted along with a recon cylinder head so have no blowby issues, but even before rebuilding my engine it never dripped oil, so I would think your engine would have to be suffering from serious blowby to lift your oil out the way it is. At every 1500klm oil change interval my crankcase filter is wet with oil and dirty but that's it.

 

[5twins]

Opening the breather up more is not a good idea. It will blow even more oil out. My guess is the 22 miles @ 75MPH. That's pretty hard running. Your rings may be wearing and allowing excess pressure build-up in the crankcase, forcing the oil out.

When I first started running my 650, I took the rubber reduction plugs out of the breather tubes. Everyone said it was OK to do. I had a small K&N breather filter on the hoses. It was always wet with oil. I read "Farrell's Shade Tree Corner" over at 650Central and put the reduction plugs back in. I added the power brake check valves. The ends are barely damp with oil. But if I did 20 mile high speed runs daily, I'm sure I would be seeing more oil there. I don't believe this motor design is ideally suited for that sort of use.

 

[Tomterrific]

A catch can with the check valve between the breather and the can. At the bottom of the can, a small hose running to the crankcase.

The can would catch the oil and the small hose at the bottom would pull the oil back to the crankcase due to the vacuum from the check valve.

Tom

 

[TurboFarviknugn]

A catch can with the check valve between the breather and the can. At the bottom of the can, a small hose running to the crankcase.

Tom

Yep going to do something similar, but no drain back to the crank case but will vent puke can back to one of the carbs just to complete the venting process and any minute amount of oil vapor will be burnt. First I am going to build a new electrics box and do away with my battery, going with the sparax capacitor opening up some space, then to fab & install puke tank.

We shall see how it goes.

 

[Sisyphus]

First thing I did was find a single spigot breather and modified it to breathe better (there's a documented mod out there somewhere). Then I ran a single tube to a catch can mounted under my seat, which now has a UNI clamp on filter on it.

Tim, where did you buy your catch can?

EDIT: DISREGARD. I found your earlier post. http://www.xs650.com/forum/showthread.php?t=22900

 

[marp68]

JCthrills Yes either breatherbox can be used. My 75 had a two nipple breather, I now run a single nipple breather. I have about 1 1/2" of hose on the nipple with a brake booster valve plugged in with a bout 18" of 3/8 gas line from the valve down behind the engine and to the right side of the frame so any oil that may drip out won't get on the tire.

My 75 also have a two nipple breather. The LH nipple has a rubber tube going down on the chain, but the RH is blocked. Should it be blocked? The reason I´m asking is that I have a small oil leak at the rear right corner of the cylinder base. I´ve tried to both retorque and change to thicker oil with no results.

/Martin

 

[5twins]

Yes, on some of the mid '70s models, Yamaha blocked off one outlet on the breather. By the late '70s, they used both outlets again but with rubber reduction plugs in them. By the '80s, they re-cast a new housing with only one outlet and a much smaller hole. The added rubber reducer was no longer required as the reduction was "built in".

 

[marp68]

The RH hole has a rubber plug that blocks it completely. So the LH hole that is not blocked works for the RH cylinder as well? At least it looks llike both holes ends up into one. What do you think, would open it up help, so that more pressure could come out faster and take the pressure away from the gasket?

 

[marp68]

It feels like that the left not blocked hole is working, since I can feel air coming out from it. Feels a bit oily. Or should it come out more in a liquid form?

 

[5twins]

Both outlets come from the same central breather chamber, there is no left or right cylinder outlet. The breather is actually fed from the cam chain tunnel between the two cylinders. Opening both outlets up fully may or may not help. I guess you could try it. You may end up with just more oil vapor coming out the breather.

Base gasket leaks do occur on these bikes. If a re-torque won't fix it then the only option is replacement. Take a close look at the area below the cam chain adjuster. Sometimes an oil leak from the adjuster cap can run down to the cylinder base and appear to be coming from there.

Oil mist is what you should have coming out the breather, not straight oil in a liquid form. If you do get regular oil coming out, that usually indicates a problem like too much crankcase pressure or too high of an oil level in the motor.

 

[marp68]

I just read the article that jd750ace is linking to, about the different types of breathers. INtresting. I understand it so that if both holes are being used, they should be used with reduction plugs. Since my left hole is completely blocked by a rubber plug and the left is not blocked, that would perhaps make it even. Or could the baffle inside possibly be faulty?

 

[wiggins]

Should just be a mist.

 

[marp68]

Ok, thanks. No it's just oil mist. I might try open the other up. The leak is definitely from the base cylinder, since it is just in the rear corner and slightly forward, not along the gasket right under the cam chain. I've just put some liquid gasket around the area to see if it helps stopping it.