IH: Engine Control - Sub-01B

Magneto Ignition System

(58-59 XLC and 58-69 XLCH) 1) 2)
The magneto produces a high voltage discharge to the spark plug which is timed to each cylinder's compression stroke.
It also eliminated the need for a battery for ignition. 3) as you can kick start or bump start the bike at about 2-1/2 MPH or less. 4)

  • Components include a single induction coil, a rotating magnet (rotor), a condenser, a circuit breaker and a circuit breaker cam. 5)
  • Ignition is timed when the front cylinder piston is 11/16“ / (45° of crankshaft rotation) before TDC on the compression stroke.
    Upon setting the proper timing adjustments at the factory;
    Timing alignment marks were stamped on the drive housing plate and rear edges of the magneto adapter plate for future timing adjustments. 6)
  • A grounding circuit is connected to a button on the right handlebar (stop switch) that breaks the circuit to the ignition and stops the engine.
  • Magneto mount changes:
    • (1958-1964) Magneto is mounted in a fixed position producing advanced spark timing only.
    • (1965-1969) Magneto is mounted on a movable plate allowing for spark timing retard.

Mounting Adapters

Seal Styles: 7)

  • A): a square section rubber ring that gets installed into the cam cover bore under the mount plate.
  • B): a square section rubber ring that gets installed into the cam cover bore. .
    An O-ring & washer installs between the top of the mount plate & the bottom of the mag (washer to mag & O-ring to plate).
  • C): a real oil seal that gets installed into the cam cover bore under the mount plate.

Cam Cover to Adapter Gasket:
1958-E1965 adapters use gasket (32522-37). 8)
The parts catalogs say the gasket was available for 1958-1969 XLCH.
However, gaskets are known to lose their structural integrity (used on movable mount systems) resulting in the hub working loose from the cover.
HD got away from the gasket in mid 1965 for this reason.
So L1965-1969 setups don't use a gasket.
A bike with no seals barely leaks because the mag drive gears don't get very much oil.
The oil they do get is “splash” oil. A very small amount of oil gets to drive gears by oil passing thru #2 cam bushing.

Screw and Washers:
The 2 big holes on the 62> mag lower housing slots are access holes for 2 of the 4 screws that hold the lower mag housing to the mag body.
L62-64 had rectangular 'washers' that straddled the big holes. 65-69 had the arm that control cable attached to that straddled the holes.
Uses #12-24 x 15/32” countersunk flat slot head screws (1865W) to hold plate to cam cover.

Fixed Position Magneto Adapters:
1958-E1962:
Used with magneto (29504-48A).
Magneto Adapter (29600-48), Oil Seal (29603-48), Adapter to Crankcase Gasket (32522-37).
1 pc mount. Mag bolts 'hard' to plate. Timing is fixed because the mag can't move once bolted. 9)
Mag to plate bolt pattern is at 12:00 & 6:00 (when your sitting on the bike looking down).
Special #12-24 slot head screws (29601-48) hold plate to cam cover. Uses 'no tach mag' and SEAL STYLE A.
Uses gasket between the mount plate and cover surface.

L1962-1964:
Used with magneto (29504-48B).
Magneto Adapter (29600-62), Oil Seal (29603-48), Adapter to Crankcase Gasket (32522-37). 10)
1 pc mount. Mag bolts 'hard' to plate. Timing is fixed because the mag can't move once bolted.
Mag to plate bolt pattern is at 2:00 & 8:00. Uses #12-24 x 15/32“ countersunk flat slot head screws (1865W) to hold plate to cam cover.
Uses tach drive mag and SEAL STYLE A. Uses gasket between the mount plate and cover surface.

Adjustable Magneto Adapters:
A lot of parts got modified by owners over the years so you could have something that don't match the descriptions below. 11)
These are the basics to the OEM moveable mount hubs:
Plain hub (no counterbore or slot) = E1965
Counterbored (only) = L1965-E1967
Counterbored and slotted = L1967-E1968
Slotted (only) = L1968-1969

E1965:
Used with magneto (29504-48B).
Upper Magneto Adapter (29600-65), Lower Magneto Adapter (29604-65), Oil Seal (29603-48), Adapter to Crankcase Gasket (32522-37).
The 1st 'movable' setup. 2 pc (ring & hub) mount. Timing screw has a spring over it to hold adjustment (for minor adjustments). 12)
Uses tach mag and SEAL STYLE A. Very rare. Uses #12-24 x 15/32” countersunk flat slot head screws (1865W) to hold plate to cam cover.
No counterbore in hub. Uses gasket between the mount plate and cover surface.
Mount plate hub height is .390“.

L1965-E1967:
Used with magneto (29504-48B).
Upper Magneto Adapter (29600-65A), Lower Magneto Adapter (29604-65A), O-ring Seal (11101), Mounting Spacer (5944), NO GASKET.
2 pc (ring & hub) mount. Hub now has a counter bore added on it's top surface to accept an O-ring with a washer on top of O-ring. 13)
Timing screw has a spring over it to hold adjustment. Uses tach mag and SEAL STYLE B.
Uses #12-24 x 15/32” countersunk flat slot head screws (1865W) to hold plate to cam cover.
Timing screw (1074W), #8-32 x 7/8“ fillister head, allows for minor adjustments.
Timing screw spring (64409-47).
Mount plate hub is height .375”.

L1967-E1968:
Used with magneto (29504-48B).
Upper Magneto Adapter (29600-65B), Lower Magneto Adapter (29603-67), O-ring Seal (11101), Mounting Spacer (5944), NO GASKET.
2 pc (ring & hub) mount. Hub now has counterbore and added slot at 12:00 to accept a roll pin that limits the amount of available timing rotation. 14)
Ring gets drilled at 12:00 for this roll pin to install into. Timing screw has a locknut over it to hold adjustment (only). FSM says no screw.
What they meant was no “adjustment” screw. Timing gets set by moving mag to plate position.
Uses tach drive mag & SEAL STYLE B. NO GASKET.
Uses #12-24 x 15/32“ countersunk flat slot head screws (1865W) to hold plate to cam cover.
Mount plate hub height is .375”.

L1968-1969:
Used with magneto (29505-67).
Upper Magneto Adapter (29600-65C), Lower Magneto Adapter (29603-67), Lipped Oil Seal (12023), NO GASKET.
2 pc (ring & hub) mount. Hub is changed again. Still has the slot but the counterbore (introduced in L65) is deleted. 15)
The pilot extension on the bottom of hub that registers into the cam cover bore is shortened to make room for the real oil seal to fit.
Timing screw has a locknut over it to hold adjustment (only). FSM says no screw. What they meant was no 'adjustment' screw.
Timing gets set by moving mag to plate position. Uses tach drive mag & SEAL STYLE C.
Uses #12-24 x 15/32“ countersunk flat slot head screws (1865W) to hold plate to cam cover.
Mount plate hub height is .250”.

1958-E1962 Magneto Adapter Plate 29600-48 16)

L1962-1964 XLCH Magneto Adapter Plate 29600-62 17)

Adapter pics from Dr Dick. 18)

L1965-E1967 upper and lower mag adapters L1967-E1968 upper and lower mag adapters 1965-1969 hub dims

L1968-1969 Upper Magneto Adapter (29600-65C) came with oil seal: 19), 1965-1969 Lower Adapter to the right 20)

Bearing and Support Housing

From 1958-1969, these parts had the same part number but the bearing support was factory modded several times.
Bearing support (29561-55)
Rotor cam end (upper) bearing (29562-59)
Rotor shaft end (lower) bearing (29563-59)

Upper bearing plate differences provided by Dr Dick 21)

Keyed Mags

The key mounted to the magneto locks or unlocks the ground to the system. 22)
When locked, the spark is sent to ground and the bike shuts off. 23)
When unlocked, the spark is sent to the mag (removes the ground) and the bike will operate.

Lights were operated by a toggle on the visor, no other key needed.
Or, no key needed as long as the mag is in the unlocked position.

Keys on mags have been known to break, i.e. stuck or worse sending there little metal bits into the mag. 24)
However, some run fine with the key.
Keys can be made / replaced (using the number on the lock) in the case of a broken one. 25)

Solid Mount Magneto

Fairbanks-Morse Magneto (keyed) 26)
Fairbanks-Morse Magneto 27) Magneto on a 72 XLCH 28)
Magneto on a 77 XLCH 29)

Adjustable Mount Magneto

AKA Retard Mag (Timing is mechanically advanced)
It's almost like a VOES switch for your mag! 30)
The Morris Auto Advance, uses a small spring under the mag base. 31)
The MM3 uses a bronze ring and a steel base. 32)
The MM2 uses a steel ring and a bronze base.
Tighten up the nuts to create a slight drag, retard the spark for starting and the vibration + the spring will advance the unit.

Morris Magneto (MM3) 33)
Keyed magneto on a 69 XLCH 34)

Timing Advance Spring

The spring used is not a heavy one.
You can use a spring similar the old carb return springs on autos. 35)

Or a simple coil hook spring: 36)
Hooked it to the bolt on the tappet block and the spring hooked to the indent for the coil bolts.
Unhook, retard, start, hook it back up.

Makeshift Advance Spring 37)

Timing Advance Cable

You can also attach a choke cable to the primary to control the advance. 38)

Or, a twist lock cable setup:

Do a search for push-pull controls and look for a locking one.
The L-bracket on the case can be fabricated to mount the T-handle cable lock.
The arm on the magneto, at the cable connect, is possibly available through a vintage parts supplier or used.
The cable is held by a pivot and a set screw. 39)

Various Documentation

Instructions for the Joe Hunt Early Sportster Magneto:
Click on a pic to enlarge: 40)


Related Links

1)
1952-1959 HD Spare Parts Catalog for all Sportster and K Models pg 19
2)
1960-1970 HD Sportster Parts Catalog pg 18
5) , 6)
1959-1964 HD Sportster 55 OHV FSM pg 5F-13
16) , 17)
photos courtesy of Ebay seller, animalhouse2010, Link to Ebay store:
19)
photos courtesy of Ebay seller, jrsvintageharley1990. Link to Ebay Store
20)
photo courtesy of TomsCyberShop.com www.TomsCyberShop.com
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