I have a 1999 FXSTB Night train as far as I know it is STD but until I pull the motor out and strip it dont know for sure. How much can a barrel be bored before it is no good or needs re-lining if it can be done or do you need to buy a barrel piston assembly. If anyone knows the hows and whats it would be much appreciated. 

Why are you stripping it?, is the compression down? you  generally get about 4 rebores of 0.010" each, if you score or damage a bore that can take 2 or 3 rebores to clean up, your dealer can tell you how many rebores or its prob in your workshop manual which you already have because you would not strip any motor without one.Take your cylinders to a machine shop for measure and inspection, he will tell you what you need to bore it to clean it up , then buy the pistons and have him bore the cylinders,  all pistons are not exact so you need to measure the piston to work out the correct clearance, i pay $90 per bore for a rebore, which is also machine honed. And while your doing that get the valves and seats refaced and some new seals. Doing it yourself allow a grand.

 I have done a compression test they were 100 and 105. Leakage test was not bad either but the biggest problem is breathing really bad and it does smoke a bit. I have a mate who does alot of heads in Perth and he is going to do the heads up. But I just think it needs a freshening up once I get it torn down I will check the bores and deside which way I will go I would love to stick some new big bore barrels on it but will decide once she is apart. I need to find someone good in Perth who don't charge like a wounded bull to do the machine work, if I go for big barrels will need to do crank case also. I ran a engine shop for a while so rebuilding engines is not difficult as long as you have the right tools. i have rebuilt harleys before but not many.

While the motors out I am going to recondition the frame it looking a little flat and needs a good respray plus some other items need attention so winter is a good time as far as I am concerned don't ride in bad weather anymore got that teeshirt and don't need another one lol