Engine full of fuel and seized up

[Bryanj]

Seen worse run OK also seen better leak.
Make sure no raisedbits and try it

[K2-K6]

I'd use something like Hylomar blue on both sides of the gasket for the above.

Talking about "selotape" coating level (from aerosol) to let dry before assembly and degrease faces with carb cleaner or isopropyl alcohol just prior to installing.

[Trigger]

Not so keen on this. Looks like it has been hacked with a screwdriver by someone trying to open it. The top end has been off before. It was covered in sealant as well. Do we think this will seal ok with new gasket?

(Attachment Link)

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Are you sure that those barrels have not been decked ? As i can see markings from a head skimming machine. 

[PJM47]

It’s possible it’s been worked before, certainly head has been off as there was a washer missing when I took it apart.
As long as we think it coukd be ok, may be with a bit of hylomar that’s a relief.

[Bryanj]

Should you try the Hylomar a BIT is the important part!!!!

[PJM47]

Should you try the Hylomar a BIT is the important part!!!!

Ok noted. Or do we think I am better off not using any sealant at all? Opinions vary.

[Bryanj]

Personalty I wouldn't as the damage is nowhere near he fire ring or an oilway

[Trigger]

It was sealed OK before you took it apart without anything. I would never use any sealant on any gaskets as, the 750 is prone to the oil jet blocking with sealant and bang goes the top end 

What jets does the head have fitted ?

[PJM47]

It was sealed OK before you took it apart without anything. I would never use any sealant on any gaskets as, the 750 is prone to the oil jet blocking with sealant and bang goes the top end 

What jets does the head have fitted ?

Not sure, is this the jet you mean:

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[Bryanj]

Thats the one, take it out and make sure the oilways are super clean, you should also fit 4 O rings, 2 at the jets and 2 in the blank recesses at other end of cam tower

[K2-K6]

Yes,  there's one for each side of the head.

Purpose is to restrict the oil flow to designed rate while maintaining pressure within crankshaft supply architecture, the cam area being low pressure as opposed to the crankshaft being high.

It's the nature of any restriction in flow that it will "collect" any stray particals (it's only fed filtered oil) resulting in impaired flow or blocking.
The risk here is to have detached and excess sealant pass onward up from gasket face and get stuck in those small restrictions.

It's your appreciation of this as to the decision you make,  blocked they will certainly trash their onward valve train,  of that there's no doubt.

I've used Hylomar spray as stated above (light spray of gasket and leave to dry) to leave a "selotape" quantity fine film on the gasket.  This primarily on the F2 engine as they are very prone to oil seeping at the head gasket,  this never with any problems.

I can see the other point or view and wouldn't argue with the logic, but know that many owners fret about any oil leak at all here at this juncture. It's highly unlikely to compromise the compression sealing of the engine (with no sealant applied) so not a worry from competent running perspective.
Of course if it does leak it's just that normally and not drastic, versus the other risks.  But naturally it's engine out to correct.

Giving a clear picture hopefully will help

[PJM47]

Ok thanks for the explanations. Makes sense. Probably safer to leave it dry.
Having had various old British bikes I’m not too concerned about oil leaks.
I will make sure those jets are clean before putting it back together.

[Trigger]

These should not leak if the studs are sealed and the O'rings are up graded 

[PJM47]

These should not leak if the studs are sealed and the O'rings are up graded 

Are the o rings that come with the vesrah 156 any good? If not would you be able to point me at suitable upgraded ones please?

[Nurse Julie]

These should not leak if the studs are sealed and the O'rings are up graded 

Are the o rings that come with the vesrah 156 any good? If not would you be able to point me at suitable upgraded ones please?

I have stock of all the upgraded O rings you need Paul. I will PM you after I've cooked dinner 😁😁😁