Technical: Ignition and Light Switches
Perry Ruiter, Jerry Raino, Dave Hennessey


1952 to 1958 - K, KH, and XL, XLH

The K, KH, and 1957/58 XL and XLH models used Briggs and Stratton # 600580 switches for both the ignition switch and light switch. These were developed by B&S specifically for Harley-Davidson. H-D identifies them as: 71500-52 Ignition and Light Switch (2).

Only nine different keys were used for these locks. The 1957 Parts Book lists: 71625-52 Switch Key (2) (specify serial No.) (H1601 to H1609 incl.)

The Secret Revealed

The original keys could be withdrawn from the lock with the switch in ANY position - left, center, or right. However, most replacement keys can only be withdrawn when the switch is in the center position. The reason is that B&S specially modified the keys supplied to Harley-Davidson to allow this. We've finally found the secret!  
This Briggs & Stratton document not only gives the "codes" for each key number, it also provides instructions for the secret modification.

Look Ma, No Key.   The secret modification works!

Identifying Your Locks

Many locks, like those on some Fairbanks-Morse magnetos, have the ID number stamped on the outer face of the lock cylinder. This is great when you lose your keys, but from a security point of view, it is not such a good idea. The locks on these ignition and light switches have the ID number on the side of the cylinder, just under the outer face, making it very difficult to see without at least removing the instrument panel cover. Of course, having only nine different key "combinations" was not such a good security measure either.

Removing The Lock Cylinder

Removing the lock cylinder from the switch for cleaning is a simple matter. Insert the key, turn it to the right, and leave it in. There is a little hole on the side of the lock body. Inside the hole, you will see the edge of a brass disk. This disk is spring loaded and holds the cylinder in the switch. Start pulling the lock cylinder out of the switch with your fingers, while simultaneously pushing on the edge of the brass disk with a pick or jeweler's screwdriver. The cylinder will pull right out, and then you can remove the key.

To install the cylinder back into the switch, insert the key, push on the brass disk with your thumbnail, and slide the cylinder into the switch.

Note: the cylinder shown at right only has three of the five "pins". A nail file or 4d finishing nail would probably work it.

Mounting Brackets

There appear to be 3 versions of the Ignition and Light switch "C" bracket. The 1959 Parts Book only reflects the existence of one version as can be seen in the attached PB image. At this time the best we can do is classify the 3 versions as “Early (A), Mid (B) & Late (C) ”.