DIY Crankcase Breather Catch Can

After doing the GAK mod to my bike I have noticed that the crankcase breather likes to spit oil all over everything when doing lots of Interstate travel at 80+ MPH.  Its usually not so bad but if doing 4 or 500 miles or more it can start to drip down the side covers and generally make a mess along with building up lots of gunk under the tank and coating the outsides of the carbs.

This was my home grown attempt to fix that problem on the cheap.

Heres what I used, a few plumbing fixtures, another new filter, and a Jim Beam salt shaker can I had laying around and never threw out aka free!

Ignore those scrub pads, Do NOT USE SCRUB PADS.    Many types of scrub pads use fine embedded abrasives which could destroy your engine if they got introduced into the oil.  Since it is hard to determine which have them and which don’t its better not to take the risk.

I had to seal up the seams on my can to get it water tight.  it was able to hold a full cup of water overnight without spilling, hopefully that should do.

I did not have much room to work with so I have the air going in from the side and exiting through the top,  many of these catch can designs use a long internal tube for the line to the bike and a short internal tube for the line to the filter.  Either way will work, you mainly want to create a change in direction for the airflow inside to help separate the oil gases from the air.

I have this side connector cocked to the side for clearance under the tank.

Testing the fit, perfect.    The only problem with this location is you will eventually need to take the tank off to drain this can.  You could also use a longer line and attach your catch can where the AIS components used to be.

Instead of using scrub pads I used a lawn mower air filter.   Since this media is designed for air intakes to begin with it should be fine for the engine and help filter out the oil mist a little better.



UPDATE:    This catch can worked beautifully for over a year but one day I noticed a few drips on my floorboards on the right side and sure enough it was coming from this catch can.  I pulled the tank to check if it was full but nope it was seeping through the seams in the can!  I hadn’t sealed it good enough.   I have removed this until I can find something else to use for the container, preferably something made in one piece with no seams.

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