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I can see the logic in a catch can for a race bike, but for a long distance bike (you know, an Airhead) I think I'd want to have that oil vapor condense and return to the crankcase. Do you have room over the trans or battery to build a breather box?

My VW breather experience would make me want to use, say, a police tank compartment for some breather volume over the crankcase, maybe move the coils forward a bit as well.

melville wrote:I can see the logic in a catch can for a race bike, but for a long distance bike (you know, an Airhead) I think I'd want to have that oil vapor condense and return to the crankcase.

Well, I can always empty what is in the container back into the crankcase, I suppose.

melville wrote:Do you have room over the trans or battery to build a breather box?

I am keeping my stock air cleaner, thank you.
I considered putting the catch tank in the tool tray, but I refuse to give up my tool tray.

justoneoftheguys wrote:

melville wrote:I can see the logic in a catch can for a race bike, but for a long distance bike (you know, an Airhead) I think I'd want to have that oil vapor condense and return to the crankcase.

Well, I can always empty what is in the container back into the crankcase, I suppose.

melville wrote:Do you have room over the trans or battery to build a breather box?

I am keeping my stock air cleaner, thank you.
I considered putting the catch tank in the tool tray, but I refuse to give up my tool tray.

Yeah, I can see your space challenges. On a VW there's a relatively enormous box for the engine, usually with substantial headspace over the crankcase.

I like the way these guys did it (click on the pic):

I thought that the venting of the crankcase into the carburetor helped evacuate the crankcase pressure that builds up. Also, it gives a secondary burn to the fumes instead of putting the fumes directly into the atmosphere.

Boy, that set-up of MattCfish looks ingenious! I mean, really!

Chuey

Chuey wrote:Boy, that set-up of MattCfish looks ingenious! I mean, really!

I did not really understand what was so special about that one. Yeah, the front cover on the rear is cool, but all I saw was a small diameter hose coming out the back and terminating, where?

Yup, I meant the front cover adapted to use as a rear cover. I would have not thought of that in my lifetime.

Chuey

justoneoftheguys wrote:Airbear, copper tubing and flaring would be very easy for me, as my neighbor is a HVAC guy! He probably even has experience with some sort of brazing. I think I've seen a small set of tanks in his van. Hmmm...

Matt, that looks like a small diameter tube. I was always under the impression one would want this outlet to be as free-flowing as possible, so I have always chosen hose with the same ID as the OD of the CC breather spigot.

The small tube is just a drain, the breather is the filter you see sticking out of the left side. Works great, and separates moisture and oil out of the minimal blow by I have. For some reason, Image shack lost my picture of the other side.

mattcfish wrote:

justoneoftheguys wrote:Airbear, copper tubing and flaring would be very easy for me, as my neighbor is a HVAC guy! He probably even has experience with some sort of brazing. I think I've seen a small set of tanks in his van. Hmmm...

Matt, that looks like a small diameter tube. I was always under the impression one would want this outlet to be as free-flowing as possible, so I have always chosen hose with the same ID as the OD of the CC breather spigot.

The small tube is just a drain, the breather is the filter you see sticking out of the left side. Works great, and separates moisture and oil out of the minimal blow by I have. For some reason, Image shack lost my picture of the other side.

Bummer about the 2nd picture. I would also be curious what the plumbing looks like!

Thank you for the explanation. I kept looking at the filter on the left side, thinking it was the left carb filter that just looked askew for some reason.

My thought:

Everyone wants to emulate race track equipment ...

The problem with a breather vented to the atmosphere,
excluding environmental thoughts,
will be finding that rare "pressure zone"
where the oil mist will be taken away from the MC
rather than being blown onto and all over it.
Typically, that place will be a considerable distance behind the rear tire ...

Why not install a catch-can into the existing closed system as a separator to collect oil
Then, rather than the small breather to vent oil mist into the atmosphere
(and onto the rear tire as it so often turns out ...),
run a return line back into the air-box ?


Your thoughts ?