What is it ?

[pd]

Just ahead of the transmission and behind the plug wires , What is that ?

[kartjockey]

Are looking at the part with three brass screws right by the short red piece of wire?  If so, that is the headlight switch on earlier bikes. My '48 has one. It is a center off toggle switch. My doesn't have a key switch but rather has a twist grip on the left handle bar to dump compression to kill the motor.  Makes a cool sound!

[pd]

That's the piece I'm wondering about .
That is on a '53 Automatic . There is a key switch , too . How long did Simplex use that toggle switch ?

Here's the page I took that pic from :

http://bringatrailer.com/2011/01/03/easiest-rider-1953-simplex-automatic/

And here's a '52 with a few alterations :

http://bringatrailer.com/2011/07/03/preservation-piece-1952-simplex/

[GaryF]

My 48 has that switch hooked to a cable that goes up to the "dash". Center position is lights off. One way is lights on high other is lights on low.

[kartjockey]

Gary,  Is that cable something the factory did?

[Mike Sal]

That switch was an interim design prior to the dash mounted multi-position ignition switch.

That 2nd link bike dosent' look like a '52 to me ('52 had a unique decal).  What do you think of that pull rope starter?  It's a shame they cut up the flywheel cover.
Mike Sal

[pd]

"What do you think of that pull rope starter? "

Innovative shade-tree engineering .

[GaryF]

I don't know if my light switch cable control is factory. I suspected it was. Where was the choke control on a 48 ? Mine has no cable and choking it puts your fingers in a precarious position.