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Engine Mechanical TopicsDiscussion for motor builds, cams, head work, stripped bolts and other engine related issues. The good and the bad. If it goes round and around or up and down, post it here.
can anyone help me with the parts number for the green o-ring as pictured, at the bottom of my cylinder (2012 Softail 103).
I can’t seem to locate the correct section in the partsfinder where it would be pictured.
Thank you! Not sure how I could have missed that one… and it turns out with Cometic MLS gaskets you are not even supposed to use this o-ring.
best, niv
You will need that o-ring for cylinder base.
You do not use same o-ring at head gasket if using cometic mls head gaskets. You still need at cylinder base
You will need that o-ring for cylinder base.
You do not use same o-ring at head gasket if using cometic mls head gaskets. You still need at cylinder base
Yes, but the head gasket goes between cylinder and head. The o-ring I was initially looking for is at the base of the cylinder, where there is no such gasket, just a large o-ring.
Yes, but the head gasket goes between cylinder and head. The o-ring I was initially looking for is at the base of the cylinder, where there is no such gasket, just a large o-ring.
Then for sure you need the Nitrile o-ring if that's what Harley specs if you base gasket is the original OEM large o-ring.
That set I show is the head and base cometic. Thought that what you had since I thought you were saying they said you didn't need the o-ring with their base gasket.
Last edited by Jackie Paper; May 29, 2026 at 11:32 AM.
When I said I did not need said o-ring I had top and bottom of the cylinder confused (don’t ask).
that said, I was not able to find anything but an o-ring from cometic for the cylinder base, at least for the bore required for my 103. And with the bore-sized o-ring, I’ll certainly need said dowel o-ring as well at the base.
at the head I should be fine without, give the MLS gasket.
best,niv
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O-ring question, cylinder base
