Using a leak down tester??

[Spanish Fly]

A lad I know had a similar leak caused by a small crack in the casing allowing it to leak through the lower left hand side stud. He cured it by using studlock as you've suggested. I'm not sure how great a repair that is in the long term but It'd certainly get you going.

Sounds likely in this situation. Leak travelling up the stud hole from crack in case thread and escaping at 1st point of exit i.e. porosity/pin hole in barrel casting. Have you checked for hairline crack in stud hole?

SF

[sydduckett]

I know you already have the kit but the easiest way is a mountain bike inner tube cut about six inches either side of the valve. Attach to stub and the other to the carb manifold using jubilee clips. Then pump up using a bicycle pump.
If you want to identify exactly where the leak is invert the top end into a water butt, put a rod\bar through the front engine rod holes so they are longer eneough to sit on the water butt edges and take the weight.
As you pump you will see the leaks just like you did when repairing holes when you werea nipper.

[Donnie]

hi all, sorry for the delay, yep, checked for hairline cracks but cant find any evidence of one, also, have acquired some gasket paper and a base packer to make my own

As for putting the top end in water I guess that could work lol.