Hi guys. I need some advice. 

Other than change your mechanic.......the kits for the most part are compatible but a decent mechanic will make sure all the tolerances are correct before screwing it together

If cylinders and piston-ring-bore clearance is checked and measured, this shouldnt happen. 

Cheers. 

As stated simply bolting the barrels over the pistons is not good practice. Why did you not get the "seized" barrels rebored and then pistons to match

Mate id be spewing. What material pistons do they run? What break in process occured?

springer88 plenty of advice here.

I would question the state of the tune.
Carb' or FI ?
What was the rest of the build specs , cams, compression etc ?
Did they warranty the parts ?
I will add that a 88" to 95" upgrade would only cost about $600 in parts, and gain nearly the same power with the right combo' .

Was it tuned on a Dyno, or on road with an AFR guage ?
Running stock ignition ?
Did you ever check cylinder head temp ?
With that setup, it really would need to have the timing adjusted compared to the stock setup.

OUCHIE! Thats a decent nip up

Grabbed the bore my arse. This is classic ...dont check tolerances before assembly.

Unless the heads were decked, the compression should be close to 10.5:1 and under 200psi cranking with the 585's.
That's exactly how I would set it it up, but the tune is the mystery.
We can go around in circles guessing, but now you need to be asking the builder some questions.

A few here obviously don't know anything about the Sidewinder kits.
Hilly is right about the steel liners.
They are the 4140 chromemoly steel liners and they have to be right straight out of the box.
There is nothing to play with if they need to be tidied up.
The piston - cylinder clearance is less than conventional set ups and a greater ring gap is also required.
As well as checking the clearance, the cylinders should be checked for roundness from top to bottom with torque plates.
If they are not right they should be sent back .
There were a lot of clearance problems and out of round cylinders about early on when HD first brought out the 110 and 117 kits.
Most Dealers bolted the kits straight on without checking anything and a few got caught.
The supplier may have been told to improve quality control because these problems became less frequent.
S&S use the same supplier.
You may have been unlucky and got a crappy set, or your guy used usual clearances and didn't check the updated specs for these kits.
S&S also specify a particular fitting for the oil control ring where other manufacturers do not .
OK, bit late for any of that.
The pictures give a few clues.
Insufficient clearance right from go or the ring gap was less than required.
The rings have overheated and expanded and generated a bit of heat in the piston and the cylinder walls.
The piston would expand a bit more than the cylinder walls, hence the wear marks on the pistons and cylinder walls.
The rings appear pretty loose in the ring lands now; probably lost their temper.
Difficult to check ccp with the EZ start cams.
Supposed to be able to check by running on one cylinder but not a good idea with a new build .
Any problems with high compression or detonation, the top ring lands will usually close up a bit.
Doesn't appear to be the case here.
Tune is pretty important when breaking in a new build. Much easier with efi these days , but I would research or try to find someone with a similar build and duplicate the carb set up until you have a chance to get your own fully sorted.
Not sure I would be comfortable with your builder .

Put the ring in the cylinder

Ring gap 18thou

Do you have installation sheet for that kit, 

Found the cause

WTF.....

Ok, maybe get builder to measure while you are there

The rings in S&S Kits still have to be gapped, they are not (nessessarily) set out of the box.