Crankcase catch can
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Stage I
Joined: Jul 2022
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From: Rochester ny
Crankcase catch can
Morning all... Looking for a catch can or alternative for my 88 sportster. I put a different air filter on the bike and had to put a breather filter in place of the hose that went to the stock air filter. My issue is now the filter spews oil down the right side on long runs over 60 mph. I've seen some cans on the internet but nothing for the older sporty's. Pic's or description of what you have would be great! Thanks!
Stellar HDF Member
Joined: Feb 2013
Posts: 3,072
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From: Dallas, Texas
Your crankcase breather system is a holdover from the 57/85 Ironhead's. So ya gotta use what works on Ironheads. Get the damn filter off it. Here's how to cure it WITHOUT a catch can or filter. From the breather outlet on the camcover, route the line to the rear of the engine, tucked it behind the pushrod tubes. Then proceed up to under the seat, where you go over the frame and drop down to the swingarm. Tuck the line between the swingarm and frame exiting under the swingarm. There is a 1 way valve inside the camcover separating the oil from the crankcase air, so it's safe to say it ain't doing it's job. Here's the logic on why this works. Oil is heavier than air, to any oil blowby will drain back to the camcover and only crankcase air will come out if the breather line.
HDF Community Team
Joined: Dec 2011
Posts: 8,592
Likes: 4,023
From: San Diego, CA
From the breather outlet on the camcover, route the line to the rear of the engine, tucked it behind the pushrod tubes. Then proceed up to under the seat, where you go over the frame and drop down to the swingarm. Tuck the line between the swingarm and frame exiting under the swingarm. There is a 1 way valve inside the camcover separating the oil from the crankcase air, so it's safe to say it ain't doing it's job. Here's the logic on why this works. Oil is heavier than air, so any oil blow-by will drain back to the camcover and only crankcase air will come out if the breather line.
Yes, my transmission vent line runs up under my seat and loops down, so any oil will drain back to the transmission. TST is just advocating the same type of fix for your crankcase vent that you may already have for your transmission vent. I have a 1991, so I think the transmission vent hose is the same setup as they used on your 1988.
I have no idea if the stock one way valve is still available, but you might ask over on XLForum.net. I think I saw a post about some kind of breather valve you can add (Krankvent??) but I'm sure someone can help you out on XLF on early Evo/late Ironhead equipment. Good luck.
John
Last edited by John Harper; Jul 24, 2022 at 12:11 PM.
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