Diagnosis time. Lower cyl:
To me it all looks fine except for the bright ring on the piston and corresponding one on the head! how the heck does that happen?
no play with the rod on the crank, could the crank have worn bearings causing that damage? (i assume its contact) This is the cylinder that doesnt belch heaps of smoke. The other one when I pulled the exhaust sloshed so i tipped it up in a bucket and got like ~50-100ml of super tar black oily liquid (the spray that was coming out the back of the bike I presume).
Upper cylinder to come soon/tomorrow: