I've been playing with my homemade breather system on my 87 LMIV with a 1400 engine. It's working well going into the original catch can I made years back but I wanted to improve it and have the option of returning oil to the sump. The lines from the heads are routed up and forward tightly under the backbone to the neck and then back and down to the can which I drain as required. I seem to get next to nothing on short rides say 25 miles or so but if I go 50 or more non stop I get some. I can only guess that it takes that long to push the oil to the high point.
Draining and discarding the oil is no big deal and mostly I don't want it back but on a longer highway trip I wanted to have the option of putting it back in the sump.
I made a can with about 6 oz capacity and it mounts just inside of the R.H. carb and K&N filter. I needed it up high like that to be able to drain back to the sump. It turned out to be a little too large and I had to cut the side off and weld a filler plate in. The bonus is this gave a view of the insides so I can clearly show the plan. There are 7 brass fittings silver soldered into the can..
2 are for the sight gauge which I managed to squeeze in at the end.
On top is a 90 degree 1/2" which takes the main breather coming back from the neck area.
Beside it is a 90 degree 3/8" which is the main outlet to atmosphere. It will go up under the backbone as well and down to the lower front of the frame. I don't expect oil to get there at all.
On the bottom are 3 more fittings:
The 1 with the stand pipe inside the tank serves 2 purposes, it is open to atmosphere and helps vent the engine and before I managed to
add the sight gauge it would have been how I would know the can was full. My old can used this method and I just left the fitting open and if I went too long without draining there would start to be a little oil showing in the rear rim.
Then there are the 2 90 degree 3/8" drain points both will have a hose from them and the one which drains the lowest point is for draining and discarding. It also is for taking a sample of what is in there and will show the presence of water,mayo etc.
If I am on a longer trip in hotter weather is when the 2nd drain with the stubby stand pipe comes into play. If the lower one is showing clean oil then the other one will be for returning oil to the sump.
The lower drain will have short hose for access below the carb with a tap so I can catch it in a coffee cup and the other will have a line with an inline tap to a fitting in one of the sump plugs.
This way I don't need a check valve as it can only drain when I choose to.
