1998-2001 Honda Fourtrax Foreman TRX450S, TRX450ES Factory Service Manual, Page 151Get this manual
CYUNDER HEADlCVLlNDERPISTON INSTALLATION
Turn the tMsioner shaft cloc w,se' with the stopper ki loof to tetract the tensionerthe insen the stopper fu llV to hol the telfl sioner in th fill retracted pos ition
TENSIONER SHAFT
STOPPEIR TOOL