You might investigate this:
https://mail.google.com/mail/u/0/#inbox/FMfcgzGwHpShGXCRfdRHVMjwPBqZtrhR

I did not do this mod. Too late for me, went another direction.

You should've pulled the liners right out here & then JM - 15 seconds for each one and that would've have told the whole story. 

Anyhow, regarding the head & valves - you're getting 'too deep and meaning full' and over doing the matter, if I may be so blunt.  Take the head, valves, springs, caps, collets, etc and new valve stem seal to a cyl head recon shop to do the reassemble & test job for much less than you're worrying about.

Ethanol makes a mess on the valves - well documented by Hamlin.

In the mean time - 

I spent last week removing all the valves, labelling  and bagging them, along with their associated retention collets, valve springs and upper retention plates. I then set about cleaning up all the carbon in the cylinder head and from the exhaust ports.
It was about this time that I started to query why I had so much carbon and in particular on the piston crowns. I did wonder if E10 played a part in all of this and whether or not fuels containing alcohol have a tendency to cause greater carbon deposits. Google helped put that theory to bed but there was no denying . . .the engine had more carbon build-up than it should but not only that, a lot of it was shale-like and loose but also, the deposits were inconsistent. At least one of the exhaust ports had no carbon in an area where the other two were encrusted . . . hmm!!!
My next port of call with Google had me researching the cause of carbon deposits under valve seats and it would seem that the most common cause is due to burning engine oil, most often as a result of worn valve guides. In this instance, the evidence is normally clear to see and results in carbon on the valve stems and around the throat of the valve - absent in my case but of course . . . . there remains another and rather more obvious cause of oil consumption with the 1050 . . . cracked pistons!! I have never been troubled by oil consumption on my bike but I don't do many miles and it's always possible that I simply haven't noticed or perhaps the problem has just become worse more recently?
Anyway - burning oil is the most common cause of carbon deposits in an otherwise correctly fueled engine but  . . . what really caught my eye was the statement that incorrectly seated exhaust valves are then subject to pitting and melting of the interface which can result in microspheres of molten metal eroding from the valve seats.  I looked at mine more closely . . . indeed, under a high-powered loupe. What I found is not confidence inspiring. . . . . .

1. Earlier on in this post I posed a question about whether or not valves are "coated". One of the reasons I did so was because I had polished the head of one of my exhaust valves and was surprised to find it had a surface texture, much like fine sandpaper. When I looked closely, the valve head was black from carbon but punctuated by a great many minute raised metallic particles embedded in the surface - only now visible as metallic having been debrided by metal polish. The appearance was like weld spatter but was easily removed with a 3M scouring pad.
2. I decided to look at the exhaust valves more closely and as the number 6 had the worst leak, took a look at the back face of the valve. In addition to the discrete carbon deposits, it has numerous small pits in the surface all around the circumference of the seat . . . not really noticeable to the naked eye but clear to see with a powerful loupe . . . . buggerations - this is starting to make sense!!
3. Next I looked at the valve inserts in the head - all look normal to the naked eye but again, a magnifying loupe tells a different story. The inlets are all as per factory - you can still see the machining marks in the metal but having removed the carbon from the exhausts, the seats have numerous small pits and pock marks.

If the metal on the valve faces comes from here, it's hard to understand how. Surely if the valve is leaking on the combustion stroke, any escaping high speed gases would squeeze through and rapidly travel down the exhaust, taking any molten microspheres with them and not  deposit them on the face of the valve within the combustion chamber???  I'm puzzled but prior to pulling the pistons, the following is my latest theory

My pistons are cracked and this likely coincides with me first noticing a long cranking cycle required on engine start about two years and around 6000 miles ago - I've just lived with it ever since.
This has caused oil to get into the combustion chambers and the deposition of shale-like carbon deposits which in turn, have caused incomplete closure of some of the exhaust valves. This has resulted in pitting of the valve seats - of the valve itself and the inserts in the head, plus the deposition of minute molten metal particles on the faces of the exhaust valves. Do note that nowhere else are these particles evident - not on the inlets valves or within the combustion chamber itself . . .all very odd.

This has been bugging me and I decided that I would look more closely today at the "scoring" in my liners.  I did state previously that it was "minimal" and couldn't be felt with a fingernail - more like wear lines. . . .I was wrong. Mostly, they are as stated but one or two do actually register with a fingernail.

It is all conjecture at this moment in time but of course, we will know soon enough. I had psychologically prepared myself to foot the bill for new liners and pistons. £900 isn't cheap but I'm attached to the bike and want to keep it. If that bill now morphs into £900 for pistons and liners, £600 for a set of valves, £1300 for a new cylinder head plus another £500 for incidentals (cylinder head gasket, valve stem seals etc etc), then clearly the economics don't stack up. In fairness, I don't need them to stack up but in this instance, the disparity will be too great to justify and I suspect there will be some great Tiger parts coming up on eBay in the not too distant future.
I'll sit it out for now . . . . pistons will be out next week and then I'll know for sure but for now at least, I think despondent is the best description of my mood.

Wear marks apparently insignificant but in hindsight . . . .




 . . . maybe not - one or two can be felt with the Mk1 fingernail!! 

I'm happy to accept a reasonable offer if anybody is interested?

Now sold.