Whilst out on a run last Sunday my Mercury cut out a couple of miles from home with no spark on either cylinder. The problem was with a connection on the ignition switch, see attached photo.
The Lucar connector has overheated and melted the plastic sleeve on the cables that link to the lighting switch and the Power Module (rectifier and Zener diode removed years ago). Does anyone have any suggestions why this should happen as I'm concerned that there may be an underlying problem which may start a fire.
The ignition circuit has the 2MC capacitor still in the circuit. This was replaced with a new one a few years ago, so I don't think this is suspect.
Philip
Switch
I used to get this on my 1968 coil ignition Matchless G15CSR, as the bracket would move, and the contacts on the ignition switch would touch the frame. The bike would cut out and stop working. I found out what it was and made sure that the contacts never touched the top frame tube any more. This would earth the ignition switch and cause it to short to an earth.
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Loose / corroded connector...
... would be my diagnosis. Am I right in thinking this is the main power feed into the switch?
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Mercury switch wire
Thanks for the suggestions, this confirms my suspicions about a poor connection creating heat. It is the main power cable and does feed the lighting switch, so carries more amps. I'll remove the old connector and solder on a new one.
Thanks for eveyone's help.
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Step Further
The above reason for this burning out is only half the truth. Yes the connection has overheated due to corrosion/tarnish on the Luca connectors but the switch itself looks like the original from 1967!! Over 50 yrs old! The rivet between the connection and the inside of the switch is also suspect. So I would recommend that you replace the switch as well. Also if you have the head light power going through the ignition switch as well then did the original set up have this? Perhaps this is a case for relays for the lights main power.
What is the ignition on this bike?
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I see a similar problem on a regular basis on the connections to my mains shower heater. Its caused by damp corrosion and a loose connection . A fresh connector and a clean up restores the action so the wife can spend aeons luxuriating in the shower. The poor connection causes resistance and resistance makes heat. Might be possible to install a relay with some soldered connections to carry the big amps?.