as sean said that knock sounds a bit ominous!
it might be simpler to fit another engine if your big end has play
you can check if theres any b/end play by rocking the flywheel to and fro with the engine in situ
im no expert btw but have worked on m/bikes &cars as a hobby most of my life
i had a kawasaki vn 1500 v twin m/cycle a few years ago the big end went on it
i managed to rebuild it myself

I've neer used a piston ring clamp. Judicious use of fingernails and a small screwdriver and plenty of patience has worked fine for me in the past.

Guess you've never worked on a British parallel twin, then?
Both pistons have to go into their bore in the barrel block simultaneously, so you'd need to dig very deep in the reserves of patience...

As luck would have it, the piston ring clamps which I had for my Triumph Thunderbird many moons ago are a perfect fit on A series pistons.

ken

hi ken, i used to own a norman, it had the villiers 2t engine, one piston up one down (2 stroke of course)
then it was bsa,s&one triumph from there on

Good morning all, well the barrels and pistons are in there is blood under my nails and one of my exhaust manifolds snapped! One of the bores has a gauge in and on this side the engine was burning oil as the combustion chamber was as black as your hat! Along with the plug. At some time someone has re tapped the thread in the opposite inlet manifold to I can't be bothered to try to get the offending stud out. I have won a pair of recon heads I will be fitting when they arrive, but exhaust has seen better days, the offside pipe in the heat exchanger where it meets the crossbox tube has a resemblance to one of mr tetleys specimens, Sam is having a rummage to see if be has one lying around up at his store, thanks Sam! I'm desperate to hear her and resolve the burning oil issue.

Comments on big ends, I have no end play on the con rods to the crank at all, would I able to feel it, if they were gone?

Is your crank out of the engine? If so,Ken may be able to advise on it.He gave me good advice when I was re building the M4 engine for my van.Trouble is,cant remember excactly what he said .I remember it involved holding one con rod and allowing the crank to dangle,then hitting the con rod with a hammerr and listening to the noise it made.
If your crank is in the crankcase then no can do .

search this site for "Dead Chicken"

"bit of a knock" if its more of a rattle can be the small end often worse on the over run, big ends on the acceleration and usually more of a "What the f**k is that!" sound

scored bores if you can catch your nail in it its toast slightly less and you may get away with a hone

that score is the the cause of the oil burning.

The crank is in the engine still, the noise is Metallicy and not that noticeable really, the score in the bore is bad! My nail certainly finds it, the bottom push rod tube seals were leaking oil to, the rings are intact, the pistons have blackened near the bottom to.

Pinking ?
could explain the scuffed barrel

Weird really as the noise seemed like it was coming from the right hand cylinder, and only seemed like from Tickover when u blip the throttle then it went, the smoke was from the left( exhaust was blowing at manifold) this was the scored side, before I whipped it apart, the clearances on the pinky side were about .25 maybe this was the reason, the gudgeon pin seemed a little reluctant to come out on this side and it had a brown ring around it where it has been in the piston about 10mm in I'd say