Harley-Davidson breathers oil catch can

FOREWORD

So, there should really be no need for this, but any time I speak with other Harley owners there happens to be someone falling from the tree and knowing nothing about this matter.

To be compliant with anti-pollution regulation, Harley-Davidson adopted the laziest solution on Earth, so that oily vapors building up into the crankshaft are ventilated through breather valves into the air cleaner, then down into the intake manifold to your pistons. This happens to cause some residues buildup in the long run you really don't want to experience.

Picture credits: user Hairy Larry from hdforums.com

Picture credits: dkcustomproducts.com

So, what are the alternatives to this mess? The first is to vent directly into the atmosphere, but this would make Greta unhappy and move the mess to your right leg. Otherwise you're gonna get creative with rubber hoses to bypass the OEM system into a catch can of some sort, to dispense oil residues according to local laws.

INTRODUCTION (BUT YOU MAY WANT TO SKIP THIS PART)

I live in the EU and as an Harley owner, each time I need some OEM or aftermarkets parts from the US my wallet cries in pain. International shipping + import duties are crazy high, making oversea markets unconvenient and local supplies few and pricey. I heard that people living in the US don't pay import taxes for shipments below 800$… that's crazy, and I hope every western civilized country will adopt same levels of exemptions some day. Anyway, there was this billet aluminum catch can from Golan I really liked but was hard to get for me. At first I drilled the bottom of a regular aluminum brake fluid reservoir, the only issue is when I need to empty the reservoir it's a mess, because it's installed upside down, so i remove the cap and the oil residues spill everywhere outta the reservoir. Then, inspired by Golan design, I decided to model my own catch can reservoir to 3D print myseld, and I am proud of the result because it's the first time I'm modeling male / female threadings working as intended.

Some early prototypes I made to get the threading to work as intended

MODEL DESCRIPTION AND OTHER INFO

The catch can is made of two parts. 

The upper part comes with a classic hose connection like those found in brake fluid reservoirs already installed on your motorcycle. Secure in place with a zip tie. Around the connector you'll see many holes for ventilation. On the other side, the hose connector protrudes further down into the catch can to ensure the oily vapors don't ventilate too close to the holes, resulting in a mess on your trousers. This can be further improved by placing sponge or cotton pieces cut into the catch can. 

The lower part is the catch can, and there is not much to be said about it. When it's filled, empty the reservoir regularly. If you are having hard time pairing the printed parts together the first time, slightly file the end of the male thread on the reservoir's cap following the chamfer and grease the threads a little to avoid much friction between parts. When screwed together they should give a snug fit, otherwise check again your printing settings.

Now, of course being close to the engine, it's better if you print this PETG or ABS. I hadn't any spare spool of them around, so I printed in PLA+ and I am gonna test its strenght in the next future. I believe it might not fail even in PLA, but I ain't sure. I printed with the following settings, 0.20mm quality and 15% infill, but you might want to twist it up a little especially when printing the hose connector. Also, print the cap upside down using supports from the print bed.

In the end if you still have no idea what I am talking about, this should go right here

HOW I DESIGNED THIS

This thing was modeled using Onshape