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Home›Repair guides›Generac›Check and Adjust Ignition Magnetos (Adjusting Magneto Flywheel Gap)

Generac GT-990 — Check and Adjust Ignition Magnetos (Adjusting Magneto Flywheel Gap)

Adjustments

For the Generac GT-990, from the Generac service manual.

Applies to: Generac GT-990 engine

Procedure

  1. Rotate the flywheel until the magnet is under the module (armature) laminations.
  2. Place a 0.008-0.012 inch (0.20-0.30 mm) thickness gauge between the flywheel magnet and the module laminations.
  3. Loosen the mounting screws and let the magnet pull the magneto down against the thickness gauge.
  4. Tighten both mounting screws.
  5. To remove the thickness gauge, rotate the flywheel.
  6. Repeat the above procedure for the second magneto.

Tools required

  • 0.008-0.012 inch thickness gauge Amazon

Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.

Specs & values

  • Magneto air gap 0.008-0.012 inch (0.20-0.30 mm)
  • Magneto gap between flywheel needs to be 0.010 inch

Source: Generac service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.

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