MUST BE USED WITH A 50MM OR BIGGER BORE CYLINDER MUST BE USED WITH A SHORT ROD TYPE PISTON !! 86Y @ HEAD_DOME'S_? RODS_LONG/SHORT_? CYLINDER HEIGHT? WHICH_DO_I_HAVE_?THE HEAD DOMES AND CONNECTING ROD LENGTHS ARE WHAT WE ARE TRYING TO IDENTIFY AND GIVE NAMES TO HERE "MODEL"____________________"WE WILL CALL IT" Z50 68 TO 81_____ (OLD_50_DOME) (SHORT_ROD) 63MM TALL CYLINDER * Z50 82 TO 87____ (NEW_50_DOME)(LONG_ROD) 63MM TALL CYLINDER * Z50 88 TO 91____ (NEW_50_DOME)(LONG_ROD) 63MM TALL CYLINDER * Z50 92 TO 99___ (NEW_50_DOME)(LONG_ROD) 63MM TALL CYLINDER * XR50 ALL______ (NEW_50_DOME)(LONG_ROD) 63MM TALL CYLINDER * ZB50________ (NEW_50_DOME)(LONG_ROD) 63MM TALL CYLINDER * CRF50 ALL ____ (NEW_50_DOME)(LONG_ROD) 63MM TALL CYLINDER * PASSPORT 80-81__ (OLD_70_DOME)(SHORT_ROD) 63MM TALL CYLINDER * PASSPORT 82-83____ (NEW_70_DOME)(LONG_ROD) 63MM TALL CYLINDER * CL70 ALL_______ (OLD_70_DOME)(SHORT_ROD) 63MM TALL CYLINDER * CT70 69-81_____ (OLD_70_DOME)(SHORT_ROD) 63MM TALL CYLINDER * CT70 82_________ (NEW_70_DOME)(LONG_ROD) 63MM TALL CYLINDER * CT70 91-94______ (NEW_70_DOME)(LONG_ROD) 63MM TALL CYLINDER * SL/XL70 ALL___ (OLD_70_DOME)(SHORT_ROD) 63MM TALL CYLINDER * XR70 ALL________ (NEW_70_DOME)(LONG_ROD) 63MM TALL CYLINDER * ATC70 73-81____ (OLD_70_DOME)(SHORT_ROD) 63MM TALL CYLINDER * ATC70 82-85____ (OLD_70_DOME)(SHORT_ROD) 63MM TALL CYLINDER * TRX70 ALL_____ (OLD_70_DOME)(SHORT_ROD) 63MM TALL CYLINDER * TRX90 ALL (NEW_70_DOME) (ROD IS DIFFERENT THAN ALL OTHERS) 69MM TALL CYLINDER