1980 900 SSD ignition switch problem

[gioto3]

Yesterday I have done the first road test ride after the first works on my just acquired 900 SSD, It runs beautifully and idle quite well. After warming the engine I stopped to a fuel station and at the moment to start again I got no contact from the key ignition switch, no GEN red light on, no signs from the starter engine. After moving a few times the cut off switch I noticed a strange short noise under the seat, I got the contact and I started again. In my garage I dismantled the cut off switch, verified and treated with antioxidant spray the contacts, and all seamed good if not for the strange noise I heard a couple of times moving the switch from off to run with the ignition switch on operating position. I started for another test ride and again with a warmed engine I stopped and discovered I had lost the contact. After some minutes of panic I was able to get the contact again but I lost it running and with some difficulties I was able to reach my garage.
When I have the faulty contact the key doesn't work also in the parking position, no lights and no light warning lamp, so I suppose it isn't the cut off switch but probably the positive red cable that comes to the ignition switch that has a faulty contact.
I had a similar problem in a bevel single fixed once replaced the cable. Where do you suggest to begin to work? The ignition switch, the cable between the switch and the connector n°11, the connector itself, the cable between the connector and the fuse n° 1 or the one between the fuse and the battery? Since the problem appears with a warmed engine I suppose it's in an area exposed to the heating of the heads. And what about the noise? Something like a short Phhhh, initially I supposed was a fuse that expired, but it wasn't
Thanks
Giovanni

[mgh1955]

Giovanni,

I'd check both the positive and negative battery leads before wasting your time on anything else. I'd be particularly worried about the negative lead. Unfortunately if it is a faulty earth lead from the battery to the frame then you might have fried your regulator.

Mick

[gioto3]

Ok Mike, thanks, I'll do.
The battery is new, so no problems with the positive lead or the negative on the battery side, maybe the problem is the negative in its connection to the frame, I'll check.
Ciao
Giovanni

[gioto3]

I checked the negative lead and it's perfect, It was rewired with a very efficient grounding. Moreover the regulator is very well grounded too.
So I think my problem is in the ignition switch and its connections.
Any suggestion will be greatly appreciated.
Ciao
Giovanni

[Lumpy]

Hi Giovani,
not sure if you have a multi meter handy, if you don`t they are a worth while investment if you own a Duc. I have had considerable success using one and methodically checking for voltage drops along the circuit. That is, starting from the battery and moving along to each connector and checking for a full 12 volts at and after each connection.

[gioto3]

Hi,
thanks, yes I have a multimeter and I used it just to find a bad contact on the positive pole, between the fuse and the connector, moreover I found a 8 A fuse in the positive pole, the fuse n°2, that should be 25 A, and that fried for this reason, luckily in the garage and not running.
Now the problem seems solved, I hope.
I only used the continuity test with the multimeter, now I'll use your suggestion to recheck the connections, very good tip, tanks.
Ciao
Giovanni