Seepage between cylinder head and head; both sides. It was the oil lines behind the heads lubricating the rocker arms. (photos added)

[p6x]

I noticed the color between my cylinder head and cylinder changing from aluminum to oily brown;

It is oil wet, so I need to change the gasket on both sides. There were no traces when I purchased the bike, and it only started to appear. Is this one of the common problem? 20 years old gasket, it almost seems normal.

Are there any specific good quality gasket you'd recommend?

 

Edited September 18 by p6x

[gstallons]

There are o-rings between the rocker arm assy. and the cylinder head that are hard , brittle and no longer doing what they are supposed to do . Look at a parts catalog and you will find them . Replace them and perform a valve adjustment while you are into it. 

[docc]

As gstallons said, #16 in the diagram, O RING (#90706203):

[gstallons]

Order plenty , they are not expensive.   Is it #16 or #21 ? Whatever it is , they are difficult to dig out .My vision is blurry right now

Thank you Docc for the technical support .

[docc]

1 hour ago, gstallons said:

Order plenty , they are not expensive.   Is it #16 or #21 ? Whatever it is , they are difficult to dig out .My vision is blurry right now

Thank you Docc for the technical support .

Ah, yes: #16 x 2 (one per head?) and #21 [O RING-VITON (#90706094)] x8 (four per head?) . . .

The #16 is the likely culprit.

[p6x]

1 hour ago, gstallons said:

Order plenty , they are not expensive.   Is it #16 or #21 ? Whatever it is , they are difficult to dig out .My vision is blurry right now

Thank you Docc for the technical support .

I have an o'ring pick. This is a survivor of my oilfield days, and a gift from a dentist. You can also use a scribe to dislodge them.

Here's the spare part nomenclature. Unfortunately, the description seems to be incorrect for both item #16 and #21.

I should order them from MGcycle, measure them, and purchase them directly from Parker...

https://www.allorings.com/Metric-O-Ring-Size-Chart

https://www.mgcycle.com/index.php?main_page=product_info&products_id=4830

https://www.mgcycle.com/index.php?main_page=product_info&products_id=1382

 

 

[gstallons]

Whew , it was a long time ago . Joe Eish stopped me from buying a head gasket for my SE and sold me o-rings instead . 25 or so years ago. 

[p6x]

2 minutes ago, gstallons said:

Whew , it was a long time ago . Joe Eish stopped me from buying a head gasket for my SE and sold me o-rings instead . 25 or so years ago. 

You just did the same for me....

[gstallons]

you're welcome

[p6x]

Turned out, the seepage was much more simple than o'rings.... lol....

Look at the culprits...

The lines bringing oil to the rocker's arms. Both sides, at the same time too. Bizarre, non?

 

[docc]

Are those "AN" fittings and can be snugged up?

[p6x]

3 hours ago, docc said:

Are those "AN" fittings and can be snugged up?

could they be JIC fittings?

I will tell you tomorrow, or else: https://www.crustycycle.com/products/copy-of-moto-guzzi-oil-hose-california-2-3-1100-sport-v11-sport-etc-01153602

 

Edited September 19 by p6x

[gstallons]

I can tell you now . They aren't AN / JIC fittings .  AN and JIC are the same. I think this is a DIN 24 or DIN 60 . I THINK some of these have o-rings and some don't . You can remove this assy and see if it has an o-ring in the hose or not.

 Very important ! When you break this loose , hold the fitting tight that goes into the head . 14mm or 9/16 wrenches . When you break this loose , hold the hose with a pair of channel/lock pliers or needle nose vise grip pliers to keep the hose from unwinding with the nut. 

W/that being said , IDK if a hydraulics shop can match you up w/the correct o-ring or not. If so , get new crush washers , o-rings and go back together . If not , get the hose assy. mentioned earlier. 

Edited September 19 by gstallons

[p6x]

29 minutes ago, gstallons said:

I can tell you now . They aren't AN / JIC fittings .  AN and JIC are the same. I think this is a DIN 24 or DIN 60 . I THINK some of these have o-rings and some don't . You can remove this assy and see if it has an o-ring in the hose or not.

 Very important ! When you break this loose , hold the fitting tight that goes into the head . 14mm or 9/16 wrenches . When you break this loose , hold the hose with a pair of channel/lock pliers or needle nose vise grip pliers to keep the hose from unwinding with the nut. 

W/that being said , IDK if a hydraulics shop can match you up w/the correct o-ring or not. If so , get new crush washers , o-rings and go back together . If not , get the hose assy. mentioned earlier. 

I remember using such connections when I was working at the AMX. Some of the tanks had a lot of hydraulics on them, such as the AMX 30 Pluton, AMX 30D. I thought we used JIC fittings on them, but I can't remember very well.

I do remember those hydraulic connections with o'rings on them, and they failled easily. Metal to Metal is best for high pressure hydraulics.

 

[gstallons]

You "probably" did .  AN (Army Navy) was developed during WWII for the military and stayed with them. JIC (Joint Industry Council) uses the same stuff for civilian use . IT is interchangeable. O-ring face seal or flat face o-ring is on a LOT of hydraulic fittings now because of assembly speed. I don't care for this too much. 

 DIN is a  European hose connection .  IDK enough about DIN fittings to explain them.