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Welcome to the forum. The piston looks re-usable, but with new ring fitted. The cylinder needs a new coating of Nikasil and would be all good.
Looks like some one has tried to revive the cylinder by giving it a "once over" with sandpaper... What has caused the damage? (the diagonal scraping). A few options:
  • No oil in he fuel (use 40:1 to be safe!)
  • Over heating of cylinder and piston (low or no water in radiator).
  • Racing engine with out air filter or no oil on the air filter. Or air filter not fitted properly.
And I have more bad news for you sadly... If the damage was caused by any of the three mentioned above your crank might also be damaged (conrod bearing). You can fit the new piston and barrel to test. But if it was my bike I would check the crank or rebuild it just to be sure...

You mention you have spark. So your stator and the coil are working.

Best of luck!
 

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Super Moderator
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I expect that when you have the cylinder and new piston fitted she will start and run. The "sandpaper" fix that the past owner has done has damaged the Nikasil coating, but given it enough of a "wake-up" to increase the compression for a short while. Once the piston rings "polished" the bore all that was left was the scoring of the coating.
 

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Super Moderator
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Could be a few issues:
  • Seized piston in master
  • Seized pistons in caliper
  • Old brake fluid. The brake fluid will with time get water in it from temperature changes and "sweating" master and caliper.
 
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