Oring boss

[jrgreene1968]

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Is this oring boss normal, to have that tiny section missing on the edge?
Pulled a top end down, and front and rear is like that

[PoorUB]

Looks like I tiny strip is missing.

[jrgreene1968]

Looks like I tiny strip is missing.

Yep, and it's like that on the front and back. The big oring on the cylinder was cut on both cylinders in that spot.

[koko3052]

Well yes they would be cut somewhat from pushing inside the "other" boss.....but I'll bet it wasn't  leaking?

[jrgreene1968]

Well yes they would be cut somewhat from pushing inside the "other" boss.....but I'll bet it wasn't  leaking?

Yeah they were both leaking. Pulled it apart for new too-end just assumed the orings were leaking due to age. Both large o rings were cut in half, right at that spot and the small o rings looked bad to.
What's a good solution to this?

[Scotty]

I wonder if someone forgot to put the big o-rings under the cylinder in and just cut them and put them in as best they could.
The small o-ring boss if it is on both cylinders might suggest they used the wrong o-ring, just a thought. 

Quick edit I just remembered Hippo's Tips from about 15 years ago and the first tip

*Use only one O-ring # 11256 on each cylinder spigot, i.e. check the old ones
have been discarded. Use one O-ring # 11273 on the oil return dowel that
has the machined grooce in the engine case for each cylinder. One per
cylinder, two total per engine. Mistakes in this area can lead to cracked
engine cases.

[Billy]

What's a good solution to this?

You can use a base gasket. Cut bottom of cylinders to re-set base height.

[Breeze]

If the "missing" piece was left intact, wouldn't it be thin enough to be a liability for breaking/bending or otherwise compromising one of the o-ring surfaces? 

[jrgreene1968]

What's a good solution to this?

You can use a base gasket. Cut bottom of cylinders to re-set base height.

I was wandering if that would work. Do you leave out the small o-ring when running a base gasket?

[Ohio HD]

What's a good solution to this?

You can use a base gasket. Cut bottom of cylinders to re-set base height.

I was wandering if that would work. Do you leave out the small o-ring when running a base gasket?

You leave both o-rings out when running a base gasket. But generally the cylinder spigot o-ring machined pocket is gone due to the cases being big bore. So you would have a small area of the case and cylinder not supporting the base gasket. I would probably trim the base gasket ID to the o-ring machined areas diameter OD.

[kd]

What's a good solution to this?

You can use a base gasket. Cut bottom of cylinders to re-set base height.

   I use gaskets with my 120 barrels.  The bases are much narrower than the stock with O-rings and no problems to date. 

Check with Cometic.  They can make these gaskets (no extra charge) in any thickness material they have available.  A clean-up pass on the bottom (and top if necessary) can be calculated to leave you with 0 deck height.   Measure what you have now so you know what you need to remove with the gasket thickness you chose. 

[jrgreene1968]

Will it matter the piece around the oil return missing? Since the base gasket wouldn't be supported all the way around the oil return hole

[BVHOG]

Had one in a few years ago that was leaking, the wrong o-rings were installed and  that piece was missing. I reassembled with the right o-rings with no issues. Keep in mind the 110 cases do not have material there between the o-rings but they run a quad ring.   Was the 0-ring squished out around the recess when you pulled it down?

[jrgreene1968]

Had one in a few years ago that was leaking, the wrong o-rings were installed and  that piece was missing. I reassembled with the right o-rings with no issues. Keep in mind the 110 cases do not have material there between the o-rings but they run a quad ring.   Was the 0-ring squished out around the recess when you pulled it down?

Yes it was, looked to be the wrong o ring to me. I'll post a pic tonight when i get home, of the small o ring. I have no idea on the history of this motor. It's a friend of mine, that bought the bike used a few yrs ago. It's been apart though

I wander if I could just use a quad ring instead of the oring?

[Don D]

Exactly, wrong oring or double orings bust them out.

[jrgreene1968]

Exactly, wrong oring or double orings bust them out.

What would be your recommendation Don?
Buddy, talked to local hd shop and they told him it's fairly common. They just put the correct o rings back in and it works
I've never run across it before though, so unsure what to do

[jrgreene1968]

Here's what I did today, trying to see if the orings would work.
I had an old set of jugs and heads, so I cleaned up the top of case, and installed an old jug and head with the proper O-Rings, torqued them down, then pulled them back off. Orings were still perfect with no cut.
So what do you think.. wishful thinking on my part? 
He will do the base gaskets if he had to, but I figured if the orings were gonna push out and get cut , it would have done it with this test?
What you think 

[koko3052]

Use the proper o-rings, torque it down & go riding!

[PoorUB]

If it was mine I would slap new  orings in, put a dab of RTV on that spot and run it.

[Hillside Motorcycle]

Bolt it back together with the proper O rings, and paint a thin layer of Permatex across the un-machined cylinder base.