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I have an oil leak in between the head and barrel on my strada.i fitted the o ring when assembling and I'm wondering whether it needs more tightening to stop the leakage.does anyone know the torque settings for the four head bolts?I was surprised to find that there was no need for a gasket.Would loosening the bolts an then retightening them help to settle the head?

Dave L wrote:I have an oil leak in between the head and barrel on my Strada. I fitted the O ring when assembling ... <snip>

Was it a NEW one from a reputable supplier, Dave? If not ...

Dave L wrote: ... and I'm wondering whether it needs more tightening to stop the leakage. Does anyone know the torque settings for the four head bolts?

I know Nigel recommends 25lb/ft. So not very much. And this from the w/case Workshop Manual - which confirms Nigel's good advice :

Dave L wrote:Would loosening the bolts an then retightening them help to settle the head?

Maybe. But see answer 1 above ...

About a year ago, to try to stop a similar oil leak I used a softer silicone O-ring at the head joint, which is working so far.

Ducati recommends Viton (DuPont) or FPM quality for these O-rings, a chemically stable rubber usable at very high temperatures. Some sorts of silicone might not be 100% resistant against hot engine oil, or the additives.

cheers Hans

This is an experiment rather than a confidently suggested long term solution.
I wanted to try a soft O-ring material because I often noticed that the standard type looked damaged upon removal.
I think that's why they often leak.
I thought silicone might take compression better without failing, but it is yet to be proven.
Silicone is softer than Viton, with pretty good heat and oil resistance, so could be a good starting point.

Ducati singles have an unusual design for housing the cylinder/head O-ring, which results in the compressed seal filling up all the available space evidently.
The suggestions I've seen from seal manufacturers is to provide a square-cornered space, not a conical one like on our singles.
A properly dimensioned square section allows the O-ring to bulge into the corners of the space while being compressed.
It gives the displaced rubber somewhere to go. With this scheme, on disassembly the O-ring looks pretty much as new, not obviously damaged.
Ducati's conical method squeezes the seal to the point that it can tear apart as it cannot happily comply with the provided space as it is compressed.
Lacking somewhere to "go", a soft material might instead compress better than the standard O-ring?

I planned to alter the conical shape to a square one, but found that it would not work due to being too close to a cylinder bolt hole, if seal manufacturers' suggested dimensions were used.
Note that unlike singles, Ducati twins have conventional square shaped spaces at the head joints.

The o ring came in a gasket set from Lacey's so I assume its good quality.Im going to take the head off,this can be done with engine in frame I think,and see what happened to the o ring.Once the oil is hot the I can see it running forward and dripping near the exhaust.The plug is very oily as well so it's definitely a leak from the oil way.Ho hum

I have replaced the o ring,which hadn't seated properly and run a line of liquid gasket on the inside of the barrel and on the flat mating surface.(I found there was also a small leak between the barrel and head).There is now no oil leak!

Wow, that's unconventional.
Gasketless cylinder/head joints are usually reliable.
Lapping them to each other is sometimes advised, but it's not possible on a Ducati due to the way the casting around the exhaust port interferes with the barrel fins.
Maybe the head surface only can be lapped using an old liner?
I hope you get a good long term result, but have you considered the temperatures your liquid gasket needs to deal with?
Permatex make a high temp copper/silicone compound for exhaust systems, could be you're using this stuff?

Dave L wrote:I have replaced the o ring, which hadn't seated properly ...

Voilà! . Mystery solved ...