TM 5-4240-501-14P CYLINDERS Plain Bearing Fig.  6 - Checking Bearing REPLACING PLAIN BEARINGS Models 9, 14, 19, 20 and 23 Series The crankcase cover or  bearing  support  should  be  replaced  if  the  bearing  is worn    or    scored.        Select    the    correct    assembly    part number by referring to the Parts List covering the engine. Refer to Table No.  3 for main bearing gauges. TABLE NO.  2 CYLINDER BEARING REJECT SIZE CHART BASIC ENGINE MODEL PTO BEARING OR SERIES BEARING MAGNETO MAX MIN. ALUMINUM CYLINDER Milli- Milli- ‘ Inches Meter Inches Meter 6B, 8B* 878 22.30 878 22.30 60000, 80000* 878 22.30 878 22.30 82000, 92000*, 94000* 878 22.30 878 22.30 110900*, 111900* 878 22.30 878 22.30 100000.130000 1.003 25.48 878 22.30 140000, 170000 1.185 30.10 1.004# 5.50# 190000 1.185 30.10 1.004# 25.50# 220000 Horiz Ball Ball Ball   Ball 220000 Vert, 250000 1.383 35.13 1.383 35.13 ALUMINUM CYLINDER Milli- Milli- ‘ Inches Meter Inches Meter 5, 6, 8, N 878, 22.30 878 22.30 9 988 25,09 988 25.09 14 1.185 30.10 1.185 30.10 19, 190000, 200000 1.185 30.10 1.185 30.10 23, 230000+ 1.382 35.10 1.382 35.10 240000, 300000 Ball Ball Ball   Ball 320000 Ball Ball Ball   Ball +Gear Reduction PTO—185" (30.10 mm) *Auxiliary drive models PTO  Bearing  Reject  size  1.003" (25.48 mm) #Synchro-Balanced Magneto Bearing Reject size 1.185" (30.10 mm) REPLACING MAGNETO BEARING Aluminum Cylinder Engines Except 171700, 191700 There  is  no  removable  bearing  in  these  models;  the cylinder must be reamed out so a replacement bushing can be installed.  Place pilot guide bushing in the sump bearing, with flange of pilot guide bushing toward inside of sump. Assemble sump on cylinder.  Be careful that pilot guide bushing does not fall out of place.  Place reamer guide bushing  into  the  oil  seal  recess  in  the  cylinder.    The reamer guide bushing, along with the pilot guide bushing, will   center   the   counterbore   reamer   with   the   opposite bearing even though old bearing might be badly worn. Place counterbore reamer on pilot and insert into cylinder until the tip of the pilot enters the pilot guide bushing in the sump.  Fig.  7. Fig.  7 - Counterbore Reaming Turn reamer clockwise with a steady even pressure until it  is  completely  through  the  bearing.    Lubricate  reamer with kerosene or Stoddard Solvent. NOTE: Counterbore reaming may be undertaken without any lubricant.  However, as aluminum material builds up on  reamer  flutes,  eventual  damage  to  the  reamer  and oversize counterbores will be experienced. Remove  sump  and  pull  reamer  out  without  backing  it through the bearing.  Clean out reaming chips.  Remove reamer guide bushing from oil seal recess. Hold new bushing, with notch toward cylinder and in line with notch on inside of cylinder, (Fig.  8, insert), against reamed  out  bearing.      Note  position  of  split  in  bushing. At  a  point  opposite  to  the  split  in  the  bushing,  using  a chisel or screwdriver and hammer, make a notch in the reamed out cylinder bearing at a 450 angle.  Fig.  8.