TM 10-3930-653-14&P (1) When  adjusting screw  handle  is turned, adjusting sleeve slides forward or backward, varying the tension of the   cam   spring.      Therefore,   maximum   engine   speed under  no-load  can  be  adjusted  by  this  means  without giving appreciable influence on the output characteristics of engine. (2) When adjusting spring handle is turned:  adjusting sleeve advances or receeds with each rotation, changing both    the    tension    and    constant    load    of    the    spring. Therefore,  output  characteristics  of  the  engine  varies  in accordance  with  the  maximum  engine  speed  under  no- load. (3) If the relative position of the cam and cam spring is changed,  the  output  characteristics  change  to  a  large extent.    But,  because  this  adjustment  is  very  delicate, avoid it as much as possible. (2) PRELIMINARY ADJUSTMENT (1) Turn  adjusting  spring  handle  so  that  active  coils  of spring are 17 to 18. (2) Turn   adjusting   screw   handle   clockwise   12   to   13 resolutions     from     the     position     where     it     would     be disengaged from adjusting sleeve. Note If mechanism has been disassembled once, restore condition of preliminary adjustment to that before disassembly.        This    will    serve    to reduce   number   of   trial   adjustments thereafter. (3) WARMING-UP OF ENGINE After preliminary adjustment, operate engine until its oil  and  water  temperatures  attain  70  to  80°  C  (158  to 176° F). (4) FINAL ADJUSTMENT Before  proceeding  to  final  adjustment,  completely adjust  engine  operation  with  respect  to  such  points  as valve  clearance,  advance  angle  of  ignition,  distributor point gap,  revolution  during  idling,  etc.    Also  be  sure  to loosen cam stopper bolt. (1) Adjusting maximum  engine  speed under no-load. a. Shift transmission gears into neutral so that engine will   bear   noload,   then   fully   open   throttle   valve    of carburetor. b. Under   this   condition,   bring   engine   speed   within allowable range (H20PU240 : 2950  3080 rpm) by turning adjusting screw handle (outside handle.) Note Turn adjusting screw handle clockwise to increase, or counterclockwise  to  decrease  engine speed.          Turning     adjusting     screw handle  by  one-eighth  of  a  revolution will change engine speed by about 30 rpm. (2) Adjusting maximum engine speed under load. (1) Shift  transmission  gears  into  neutral.    Fully  open carburetor  throttle  valve  under  a  condition  where  mast assembly  is  tilted  fully  backward  with  hydraulic  control lever. a. Adjust   engine   speed   by   turning   adjusting   spring handle  (inside  handle)  so  that  engine  speed  is  within allowable  range  (2,800  to  3,000  rpm).    Then  re-adjust maximum engine speed under no load. 4-81