A leak is a leak, and looking at your pictures it's a leak that can be fixed.

Sure, it's a royal pain in the arse to go pulling the cases apart right after you've recently put them together, but a if you're doing a job then it's worth doing it properly.

A bit of advice. When I'm building a motor I'll be sure to check that the case halves are 100% flat. I've got a nice ground surface plate, but a thick plate of glass will also work well. Just sit the case on the plate and check with a 0.05mm feeler. If you get a high spot then check to see if there's any bumps or burrs that could be holding the cases apart onve assembled.

I then run over the halves gently with a fine oil stone. This will clearly show up high spots (which can be carefully stoned flat again), and also gives a good surface for the case sealant.

When the seals are fitted to the new crank, I make sure that they're greased, inside and out. This helps the seal located nicely on the crank and in it's housing. I also grease the centre o-ring to (hopefully) avoid any nicks when the cases go together. I use a specific low viscosity seal grease, but lithium based grease works well.

Next job is to thoroughly clean the cases. I wipe the sealing faces with a contact cleaner to ensure they're grease free and dry.

A good sealant is essential. Cheap goo like Threebond 1104 does the trick and is resistant to many solvents etc, but I hate the stuff. I use Threebond 1207 (Bloody expensive, but HRC use it and so should you!). Don't need a huge amount. I put a little blob on one finger and then kind of tap a little drip onto the case face and then sort of tap it around with a spare finger. It's more like colouring the surface really. I do this to both halves. Oh, and I wash my hands first so that there's no chance of contaminating the sealant with oil. It's actually the only time ever I wash my hands!

I then cheat a little and put some extra (not a lot) around key points like the edges of the transfers, up near where the case halve meets the cylinder gasket face, and also the edges where the main bearing outer races will be.

Before fitting the three dowels I give them a roll around in some grease just to stop them seizing.

Next the crank is dropped into the lower half. Be sure to pay attention to locating the outer crank seals perfectly. I even press the crank down by hand to make sure they're home and true.

Slap the top half on, pushing it down as best you can.

Fit the M8 bolts and slowly pull the cases together using a low torque at this stage. Just enugh to nip them all up starting with the centre two bolts and working outwards diagonally. Now give the crank a bit of a spin to check it's free. It might feel a little tight at this point but it'll loosen up when the cases are together properly.

Sticking with the inside to outside routine, I start at around 15Nm, then 20Nm, 22Nm and finally 25Nm. Between each sequence I'll give the bottom of the case a jolly good smack with a mallet to make sure it's all stress free and located properly.

With that bit done, fit the 4x M6 bolts and tighten to 12Nm.

Now, be a good chap and wipe off any sealant that's squeezed out. If it's done correctly there should be hardly any.

Insulators can be really annoying, as they will have bent over the last couple of decades. Some seal, most don't. The recommendation is 12Nm, but I rarely get near that. Somewhere between 7~9Nm usually does the trick with a bit of sealant.

I don't think it's essential to use sealant when fitting the cylinders, but it can't hurt. Maybe where the two halves come together on the front cylinder gasket face, and at the same point on the top cylinder gasket face. Just to be sure!

Torque the cylinder down diagonally across. I nip it down first, and then step up; 15, 20, 22, and finally 24Nm.

I never use any sealant on the head gasket. If it leaks with a new gasket then something's wrong, and you may have to lap the top of the cylinder and head. For lapping, I use a convenient plate of glass, and then mixa little fine valve grinding paste with engine oil. Don't get over excited with the grinding paste. A tiny dab will work. Slow and methodical is the best approach with lapping......"feel it cut", as my old engineering instructor used to say. It doesn't take long to get a perfect seal.

Head is torqued to 15, 20, then 22Nm. Again, across, not around.

Well, that's about it for today chaps. I might have forgotten something, but you should now have the perfect, leak free bottom end.