Cylinder stud oil transfer bushing?

[alzcbz]

Tearing down my 73 CB350 motor, I noticed two of the cylinder studs have some sort of silicone bushing on them. Doing some searching, found out these have some oil transfer effect.
One of them is damaged, maybe previous owner tried to remove it. I can tell the motor has been disassembled before.
Is this essential to oiling? I do have a couple spare motors I could steal one from if I need to.

 

[alzcbz]

I took a look at my spare 73 CL350 motor and it does not have the bushings on the studs.
Looking at a Honda parts diagram shows both with the bushings.
Anyone care to comment?
90034-286-020 is the OEM part I am looking at.

 

[alzcbz]

Doing a little more digging suggests, these bushings on the two outer front studs may just be for vibration.
I don't think I will worry about it.

 

[xb33bsa]

you need them in there bud

 

[alzcbz]

What is their purpose? I see no signs of oil passages through the front outer studs.
See this thread: http://www.hondatwins.net/forum/viewtopic.php?f=44&t=15854&p=140023&hilit=stud+seal#p140023

 

[xb33bsa]

what i meant is you need 2 of the "bushings" and 2 of the rubbers one each on the rear studs not front

 

[Redliner]

On the 350 twin, the rear two bolt passages are used for squirting oil to the top. This is evident in the bolt plug right of the points cover on the cam housing. Supposedly you remove this plug to bleed air out on a rebuilt engine, but I believe it's actually there to monitor pressure on the top end. In normal running, you should get regular spurts from this hole.

The front two bolts have zero effect on oil. None. Even if oil got into these passages, they would fill up and go nowhere.

Those bushings are described by Honda as, "vibration dampeners." It took a lot of research to get that official designation.

If one is damaged, scrape it off and put a nitrile o-ring in an appropriate size on the stud. Must be somewhat tight to keep it from wandering/falling. The rubber should be located in the upper part of the cylinder, close to the deck.