One thing that comes to mind is the throttle/shifter lock above the shifter.  Has it become stuck?  I’m in the middle of an RJE-19 (Javelin) restoration.  It’s a 1957, but the ’59 should have the same part.  I am using parts for the restoration from an RDE-19 I had sitting around. Here is one photo from the RDE-19 tear down which shows the throttle/shifter lock.  It just seems like the easiest thing to check.

tinkerman,

I’m happy to hear that you found the problem.

As for the kill switch, are the wire ends cleaned and tight?  If so, the contacts on the inside may be corroded.  You can rule it out by replacing the switch wires with a couple pieces of spare wire laying around.  If the engine dies when you touch the two wires together, you will know that the switch is bad.

The mercury switch you showed in your picture is actually a vacuum cut-out switch.  As fleetwin mentioned, it stops the motor from over-reving if you shear a drive pin on the prop shaft.  There is a diaphragm and a spring inside it that will ground out the ignition if it produces enough vacuum from the crankcase.  It can be, and often is, bi-passed because they can cause issues.

• This reply was modified 2 years, 8 months ago by JZago.

There should be two mercury switches on your motor if it’s electric start. One of them prevents the starter from working  if the throttle is open too far. The other one is wired into the vacuum cutout switch circuit which prevents the motor from running away or over revving with the throttle closed.

If you are adventurous and like to live on the edge,  you can either bypass them or  remove them altogether, especially if they don’t work anymore.