Jump to content

Cylinder Head Oil Return Collar/O-ring

Recommended Posts

Can someone confirm that these are the two o-rings that go around the oil return in the head?  The smaller one (#4) is referred to as the collar and is green in color, and the larger one (#6) is black and is called an o-ring. 

 

 

CylinderHeadCollarOring_2.jpg

20170420_184136.jpg

Edited by mossman77

Share this post


Link to post
Share on other sites

I can tell you the smaller one "the collar" actually fits the inside diameter of number 6 in the diagram. It helps keep the shape of the o-ring. So basically #4 and #6 make one piece that sits in that round recessed area in the bottom of the head

Share this post


Link to post
Share on other sites
36 minutes ago, Hndyman55 said:

I can tell you the smaller one "the collar" actually fits the inside diameter of number 6 in the diagram. It helps keep the shape of the o-ring. So basically #4 and #6 make one piece that sits in that round recessed area in the bottom of the head

That's what I thought.   Thanks!

Edited by mossman77

Share this post


Link to post
Share on other sites

Yes those go between the cylinder and the head. There is also an o-ring under the cylinder head but no collar is used

Share this post


Link to post
Share on other sites
43 minutes ago, Hndyman55 said:

Yes those go between the cylinder and the head. There is also an o-ring under the cylinder head but no collar is used

Yep.  I noticed that (#7).  I inadvertently cropped it out.  Here's the full diagram.  Another question, what's the purpose of having only the one copper washer on the bottom left of the valve cover?

 

CylinderHeadCollarOring_2.jpg

Edited by mossman77

Share this post


Link to post
Share on other sites

That copper washer is also a seal to keep oil from coming out of the oil rail? That bottom left stud I believe is in an oil galley that feeds the head. So it seals like a oil drain plug with a copper washer. Now don't ask me why there are 3 acorn nuts and one hex nut for the head!

Share this post


Link to post
Share on other sites
9 hours ago, Hndyman55 said:

That copper washer is also a seal to keep oil from coming out of the oil rail? That bottom left stud I believe is in an oil galley that feeds the head. So it seals like a oil drain plug with a copper washer. Now don't ask me why there are 3 acorn nuts and one hex nut for the head!

The 2003 I am working on has 4 acorn nuts.  It has a big bore kit on it though, so that may be why it's different.

Share this post


Link to post
Share on other sites

Mossman, would you mind measuring the OD of that "green collar" you refer too in the first post?

Share this post


Link to post
Share on other sites
Mossman, would you mind measuring the OD of that "green collar" you refer too in the first post?

Are you wondering if that is the green o-ring that goes on the lower left cylinder stud?

Share this post


Link to post
Share on other sites
23 minutes ago, Hndyman55 said:


Are you wondering if that is the green o-ring that goes on the lower left cylinder stud?

Not really wondering, I know it goes on the lower left engine stud, due to the square-edged shape of it. The collar that goes inside the o-ring for the oil return passage is made of steel. If Mossman posts up 9mm as the OD, that'll verify it.

Share this post


Link to post
Share on other sites

Yes that would be good to clear up

Out of curiosity what happens if the oring around the engine stud isn't installed? I redid the top end on mine but that oring wasn't supplied in the kit so it was never installed. There are no oil leaks anywhere and has been running fine for a few weeks so far with no issues

Share this post


Link to post
Share on other sites

I would think over a period of time you would have a leak develop, either externally and be able to see it, or internally and seeping into the cylinder/combustion chamber, making the bike smoke.

Share this post


Link to post
Share on other sites

I take that back I did actually put an o-ring I found from an automotive a/c o-ring kit in it. However it was loose fitting but I think it was just thick enough to squeeze down. But I will keep my eye on those things you mentioned

Share this post


Link to post
Share on other sites
Quote

The collar that goes inside the o-ring for the oil return passage is made of steel. If Mossman posts up 9mm as the OD, that'll verify it.

I thought the black o-ring and green collar are what go in the oil passage return?  I don't see any steel o-ring.  And I didn't see any o-rings on any of the studs.  Just three steel washers and a copper washer followed by the acorn nuts.  Now I'm really confused.

Share this post


Link to post
Share on other sites

Have you reassembled the top end back on the cases yet? If not, measure the green square-edged o-ring for the OD (outer diameter). If you read closely in the parts description under the microfiche diagram linked below, you will see that part #4 listed as: Collar (14.8mm) and part #6 listed as: o-ring (14.5mm). part #4 fits inside of part #6, the o-ring has an inner slot that the collar goes into. Some older Honda models use an o-ring on the lower left engine stud that fits into a slightly larger hole in the head gasket, and goes between the cylinder and the head. Other models do not use that smaller (9mm) o-ring. 99.999% of all of the aftermarket gasket kits for the top end have the two larger o-rings for the oil return passage without using a collar insert, and those kits also have the green o-ring included, but you do not use it if you cannot insert it in the new head gasket engine stud hole.

XR/CRF50 cylinder

Share this post


Link to post
Share on other sites

The green o-ring fit inside the black one and they both fit in the oil passage, so I used both.  I snapped a photo and will post it later once my phone is charged up.

Share this post


Link to post
Share on other sites

Hopefully, the green o-ring won't end up in your crankcase

Also, it looks like an aftermarket cylinder, possibly a 52mm for an 88cc kit? My guess is that you used the aftermarket gasket set that came with it?

Edited by dirtbkr188

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:


×