The crankcase breather is clean. Thanks Iron. Valve clearances are spot on. I did check the valves,stem specs, the valve bores, new springs, The piston bores looked so good and the rings looked so new I ASSUMED they were good ( trying to save money).
Can you recommend piston manufacturers?
So old rings being replaced can solve that amount of oil leak?
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If the valves and guides are good then there’s only a couple of places the oil can come from and that’s your head gasket and/or head bolts (all cured now with skim) pressured breather back into the carbs (all clean so sounds ok) or pistons/bore/rings.
Did you feel the valves in the guides with the springs off? No wiggle movement at all? Lots of blue (oil) smoke on start up would suggest oil running down through the valves and sitting on the pistons rather than coming up from the crank.
But if you’ve done all above then it’s gotta be coming up through the rings.
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Were they gapped and lined up properly?
Hahaha! Tkankyou for reviving the thread, I just seen that lady on the train again 
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I lined em up correctly but I didnt cap em cos I didnt change em that time.
Quite willing to go in and do, new rings new valve stem seals.
Just want this time to be the last time for a while. So new pistons and a re-bore are not out of the question.
They are however expensive enough to warrant a careful reflection of what exactly is required.
Compression and leak down test tomorrow.
Shes purty. 
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Tis our Linda with a little red gift on her right arse cheek.
Make sure you listen to the inlets and exhausts when doing that leak down.
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Dont know what to do next, does the last pick show to large a ring gap ( sorry thought pic was better,gap is around 3mm when squeezed in. The compression figures were obtained from a hot engine at “full throttle”.
Bore looks clean.Sending off today for bore measuring tool.
The black dot on the bore is just a spec of dirt.
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You was going to do a leak down test, what did that show? Did you have a listen to inlet and exhaust?
The compression tests are poo, you should be double those figures on a Japanese machine.
I’m assuming you turned the engine over 7 or 8 times to get the figures.
Did you try again after dropping a bit of oil down the plug hole? What were those figures?
Did you get a photo with the head off showing head gasket and tops of pistons? Was there oil sitting on the pistons and/or on the head gasket?
The ring gaps are measured with the rings off of the piston and pushed down the barrels to where they would be at around TDC and square to the bore. Do this by pushing the ring down with the piston upside down. Or just measure it down about 50mm all the way round. Then measure the gap - it should be in the specification section of your manual. You cannot check the gap with them still on the piston. 3mm is miles too big - well about 2.5mm too big.
The bores are really nice, no discolouration, no scoring, no pitting. The pistons look good too.
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What Iron said, those readings are low, would expect 130 ish, plugs wet and sooty, are you sure you paired the rings/pistons/cylinders correctly?
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No I was so peed off with the figures, I did not do the leak down ( not intentionally), I just started taking it apart. I already know all the valve specs are within tolerance and will rebed the valves and reseal the stems on rebuilding.
The pistons have not been cleaned they are coated lightly with oil. HUH !
Yeah, I guessed the gaps looked big ( on the pistons) .
The bores are great and pistons clean.
I will now take it to the engineer to have the bores measured, its £30.00 for a tool and I dont think the shop would charge much more. Then they can hone or rebore as required, and I know its good.
Worried about them not being round. Thanks.
I didnt touch the pistons/rings, last time (mistake) just skimmed the head and changed the stem seals (miser).
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Just been down the garage and pulled some old Triumph pistons out of the scrap bin.
You can see the gap in amongst the rust. They would’ve been smaller than that when set.
Sorry, only have Triumph specs but they are 12 to 18 thou (that’s less than half a mm).
wow Thanks for doing that Iron, nothing like a visual. to spell it out. I did guess that was a too large gap now I know. Was that a glimpse of light. I will try to take a better pic tomorrow.
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So just a quick update, Went to the machine shop. The barrels are oval front to back, and enlarged bottom to top. The pistons are toast too. So its a re-bore then. Just going to stick to 750cc cos the head has been skimmed previously. Thanks for the advice. Any opinions on IMD Pistons?
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Do you know if you’re going up 1st oversize or 2nd? I know theyre not cheap but wiseco would be my choice.
0.5 over. Cheers.
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