Service Manual — page 284 of 715

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5-34 ENGINE TOP END
Valves
Operating Procedures
•Clean the seat area carefully.
•Coat the seat with machinist’s dye.
•Fit a 45° cutter into the holder and slide it into the valve
 guide.
•Press down lightly on the handle and turn it right or left.
 Grind the seating surface only until it is smooth.
                            NOTICE
    Do not grind the seat too much. Overgrinding will
    reduce valve clearance by sinking the valve into the
    head. If the valve sinks too far into the head, it will
    be impossible to adjust the clearance, and the cylin-
    der head must be replaced.

• Measure   the outside diameter of the seating surface with
  a vernier caliper.
    If the outside diameter of the seating surface is too small,
    repeat the 45° grind until the diameter is within the spec-
    ified range.
      Widened Width [A] of engagement by machining with
      45° cutter
      Ground Volume [B] by 32° cutter
      32° [C]
      Correct Width [D]
      Ground Volume [E] by 60° cutter
      60° [F]

• Measure   the outside diameter of the seating surface with
  a vernier caliper.
    If the outside diameter of the seating surface is too small,
    repeat the 45° [A] grind until the diameter is within the
    specified range.
      Original Seating Surface [B]
                              NOTE
    ○Remove all pittings of flaws from 45° ground surface.
    ○After grinding with 45° cutter, apply thin coat of machin-
     ist’s dye to seating surface. This makes seating surface
     distinct and 32° and 60° grinding operation easier.
    ○When the valve guide is replaced, be sure to grind with
     45° cutter for centering and good contact.