Regrettable Engine strip down !!!! I think

Well after many years of thinking i have a over fueling problem ! I think I have a more major problem. 
Black smoke from 1 and 2  also 5 and 6 , the latter  not so bad. 
Plugs have to be cleaned every 50 miles, when that is done it performs really well up to 50 miles, then starts popping and banging from 1 and 2. The bike never starts well from cold, I have to use easy start.
i have pressure tested when engine is warm, all cylinders between 110 to 120 psi. Valves recently re-shimmed all checked out OK.

The Bike was run last week. When up to temperature I turned it off and noticed a drop in the oil level !  and it was only running for 15 minuets. I decided to remove all plugs and then inserted a bore scope. Cylinders 1 and 2 when the pistons where moved to the bottom of their stroke you could see a ring of oil running down the cylinder walls !!!
The walls of the cylinder look ok, with no bad marking. As said this was done with the bore scope.
So can anyone shine a light on this please. Could this be the valve stem seals ???, as i know this bike runs with high oil pressure. The engine has never been taken apart as far as I know.
I have been very patient with this bike for many years now, if it was anything else I would have sold it by now.
Thanks in advance for any help you may provide.
 

I'm going to guess that when you did your inspection, the bike was sitting on the side stand. If that was the case, oil sitting in the cylinder head would have gathered around the valve stems on cylinders 1 &2 and likely the oil seeped down past the valve seals and sat on the piston.
A leak down test would help confirm the problem But when you witness wet cylinder walls, it's very unlikely that it is a piston ring problem  and the compression test is good.

From my point of view, everything points to valve seals.

Hi Kawboy, the bike was on the main stand on my bike lift at the time. So leak down test I've heard of this, can i find this info on here please.

Thanks for the info

Youtube video on leakdown testing

This guy does a pretty good job of explaining how to do a test although he failed to mention that a cylinder head gasket can also be a problem and checking the cooling system for air bubbles is also an indicator.

Leak down testers can be had for $60 and up.

Cylinder pressure testing can tell you if you have a problem , where as a leak down test will tell you exactly where the problems are. I can't be bothered with the compression test anymore and I go straight to the leak down test.

After breaking in a new engine, I do a leak down test to get a baseline of a fresh new engine, then periodically, I do a leak down test and compare that reading to the baseline reading. It helps determine when I will need to tear down an engine and rebuild.

Hi Kawboy, just seen the video. Brilliant, got to get these tools. don't know why I've been messing around for so long.
Many thanks again