WITH THIS LISTING YOU GET A NEW CYLINDER 54MM BORE -- A NEW MATCHING PISTON KIT AND TOP END GASKET SET THIS WILL FIT : ALL TRX90'S HOW EVER YOU WILL NEED TO DO SOME DREMMELING TO REMOVE SOME ALUMINUM IN THE CASE OPENING,, SEE THE PICTURES THIS CAST IRON CYLINDER LOOKS LIKE THE STOCK CYLINDER BUT SAYS 107 CM3 ON THE TOP RIGHT SIDE. THE CYLINDER IS MADE BY LIFAN ENGINE COMPANY, THE PISTON KIT IS MADE IN JAPAN, SO THIS IS A HIGH QUALITY BIG BORE KIT SOME TRX90'S HAD AN AIR PIPE GOING TO THE STOCK CYLINDER TO HELP WITH EMISSIONS, THIS ONE DON'T IT IS LIKE THE FIRST YEARS OF TRX90'S THIS IS THE 69MM TALL CYLINDER AND THE BOTTOM OF THE SKIRT MEASURES 56.24MM WHERE IT SLIDES INTO THE CASES. WHEN DONE REMOVING THE METAL BE SURE THE CYLINDER BASE IS COMPLETELY FLAT WITH THE TOP OF THE CRANKCASE AND HAS SOME WIGGLE ROOM (1003E_TO54MM/1-56/1004D_TOPEND) @ WHERE ALUMINUM MUST BE REMOVED (YOU CAN DO THIS WITHOUT SPLITTING CASES IF YOUR CAREFUL) @ WHAT ID LOOKS LIKE WHEN DONE (DON'T GO TOO DEEP BY THE STUDS, BUT BE SURE THE CYLINDER DON'T TOUCH WHEN PUT BACK ON) TEST IT WITHOUT THE PISTON IN PLACE FIRST