Refitting the engine

You can fit barrels and maybe head on first, BUT the problem is holding the plot still while you do it. If the cases are in the frame it might be awkward BUT at least the plot stands still while you 'fiddle'. Dropping the head on finally is reasonable straight forward. Having/getting a good engine stand is the first problem.

I fitted my barrels and head back on with the bottom half of the engine in the bike (850 Mk3). Too much weight otherwise for me at least to fit the whole engine in one go without any help. Also, I used this method (link to video below) to fit the barrels. Makes it a very easy job.

https://www.accessnorton.com/NortonCommando/installing-barrels-with-two-hands-and-no-ring-compressor.24859/

I fitted my MK2a engine complete last week with help of a mate due to weight. I have used this method quite a few times and it is easy. Fit the front Iso mount on the engine and put the engine in from timing side and fit the x 3 rear studs to engine mount, gearbox already fitted. Then jack the engine up to fit the large Iso through bolt at the front. Job done.

Following a recommendation from a very experienced local engine builder I fitted the new pistons into the barrel on the bench first.  Since I was doing this on my own I then used four lengths of M6 studding, plus nuts and washers, to make four adjustable “legs” to take the weight of the barrel then adjusted the length of the legs so the gudgeon pins were lined up with the con rods.  Remarkably painless….

When I rebuilt and fitted mine a few weeks ago I also fitted the engine complete. Yes it is a heavy lump but with a bit of planning it works for me.

I also fitted the head to the barrel and then fitted that whole assembly to the crankcase. It works for me anyway. I first did this with a Commando I had 15 years ago then repeated it with 2 different G15s I had.