Restoration questions

[Bomberman]

Been a while since I posted, been a long while since I last rode :p Anyway, I have a TZR125 and at the moment she looks like this....

https://i1238.photobucket.com/albums/ff482/thebdaman/Bike%20Restoration/Missingbits.jpg

Pics in sig. of how it was before. Long story, travelling, moving houses/cities, laziness, no garage.... So been stood a long while (5 years pretty much), none of the liquids removed I used to fire her up and run her about a few times a year but not for a while now. My parents are selling the family house, so I had to get it out of their garden (only space large enough I could keep it).
Was torn between flogging for parts or rebuilding. With nowhere to work on it the sale seemed the only sensible thing to do. Then I managed to find and rent a garage like 40 yards from my house, so it's on!
She wouldn't start, and no lights (shock). New battery, and lights! No start though So the teardown begins!
Tank off and drained. First bad sign. Rust (lots) in the old fuel. Cleaned the tank out, fuel tap etc. Air filter/box off and cleaned. Then the carb. Worried about this given all the shit in the tank, but it seems clean after stripping and cleaning Expected tons of rust and crap in there but it seems OK! Manifold and reeds seem totally shit free too
One thing I was really worried about was the state of the cylinder. I could crank the kickstart with my hand with so little resistance it was a pisstake so I figured when I got it off I'd find it scored to buggery...
https://i1238.photobucket.com/albums/ff482/thebdaman/Bike%20Restoration/Pistonin.jpg

https://i1238.photobucket.com/albums/ff482/thebdaman/Bike%20Restoration/Barrel.jpg

This looks surprisingly OK to me (in person it looks new, I'll get a better pic)? Piston too

https://i1238.photobucket.com/albums/ff482/thebdaman/Bike%20Restoration/CleanPiston.jpg

Any reason I shouldn't just chuck that back in? Do I even need to replace the rings? The piston had some cokey deposits on top but they came off easy with some degreaser and a soft pad. (Got pics of the cokey stuff it anyone needs to see it). So what could have been causing the really poor compression? Any ideas?

Lastly, cylinder head;

https://i1238.photobucket.com/albums/ff482/thebdaman/Bike%20Restoration/Cylinderhead.jpg

How's that look? Good colour?

My questions are;
Poor compression? Why so?
Rusty tank, is this a good way to fix? https://www.frost.co.uk/automotive-tanks-products/por15-motorcycle-fuel-tank-repair-kit.html (POR15) Replacements are just too hard to find now. And costly
Anyone know where I can find replacement parts for a Mikuni carb? The needle is bent, the gasket ballsed and a new choke would be nice
Anyone know somewhere good I can get stuff blasted and coated in Sheffield?

I'll probably have plenty more, but that'll do for now I think
____________________
'Allo! My name is Inigo Montoya, you killed my father, prepare to die!
'89 TZR 125 - '94 GPZ500s - ZK3 GSXR600 Alstare

[Dazbo666]

[Frost]

[Dazbo666]

[Suntan Sid]

If your interested, I've got a tank for that, slight dent in it but an easy fix, you can have it if you're prepared to pay the postage, (around£40).

See this thread, for details:-

https://www.bikechatforums.com/viewtopic.php?t=200166&start=50
____________________
"Everybody needs money, that's why they call it money!"

[Bomberman]