Wisconsin — Servicing Magneto Breaker Points
Adjustments · Fairbanks-Morse Type FM-X4B7D magneto
From a Wisconsin service manual covering: FM-X4B7D, V-460D, V-461D, V-465D, V460D, V461D, V465, Y-128-S1, YB-85A. Check it applies to your exact model before use.
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Before you start
- No attempt should be made to oil or grease the magneto bearings.
- Field service not recommended; replace cam wick only with factory impregnated wick.
Procedure
- Remove end cap cover, distributor rotor and end cap.
- Inspect breaker points for pitting, oxidation and shorting; replace if worn or shorted.
- Take out breaker arm terminal screw releasing breaker arm spring, coil lead and condenser lead.
- Remove fulcrum pin snap ring and slide breaker arm off fulcrum pin.
- Remove contact support locking screws and lift off contact support; install new points in reverse.
- Adjust points to 0.015 inch at high point of cam using screwdriver in support bracket slot.
- Clean points again before sealing the magneto.
Tools required
- Screwdriver Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Breaker point clearance 0.015 inch at high point of cam
Source: Wisconsin 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.