A friend of mine has a V50 Monza that has an intermittent ignition issue - its fitted with a Lucas Rita System - there appear to be diodes fitted in the earth wires of the two coils. These connect between the coil earth and the Rita box. Both look a little tired and burnt. Genuine Lucas replacements seem unobtainable (we have searched the part number) Does anyone on here have experience of the Lucas system and know if there is an alternative part available.
Russell
Rex Speed shop seem to be the people to talk to about Lucas Rita these days. They sell most spare parts, even new improved circuit boards to go into the main box.
Have a read of these 2 links, hopefully they will help.
Sounds like the 2 x 12V coil variation - where isolating diodes must be used otherwise only one coil will spark. If you test the coils’ resistance and they’re about 3 Ohms, then they’re 12V coils.
Alternatively you could use 2 x 6V coils in series instead, which won’t need the diodes. Personally having used one of these before I would favour that, the diodes version always felt like a bit of a bodge-up to me.
Also check the 5-way plug block in the Rita sub-harness for bad connections. Mine ended up very tarnished and brown (originally just bare brass I think) and I ended up cutting the wires and soldering them together to guarantee no further issues with the connector.
HTH
Initially I had them on my Nevada(RITA fitted), and now I can’t remember, whether they started to smoke during my 12V coil trial or before/after that, when 2x6V coils were fitted? Anyway, 6V coils are still there, and I am quite sure I have just kicked those resistors out. Unfortunately I cannot confirm right now as bike is parked in much more weather-promising regions.
Thanks all for the info,
My friend ordered two new diodes of another brand that have the correct spade connectors alreadt fitted. I’ve passed on the the links to the owner to assist with diagnosis.
The diodes on his bike look burnt like those in the photo above. Hopefully new diodes will sort it.
Many thanks
Russell
Please keep us informed. Not much info of this type around!
That looks like a classic case of the spade connectors went high resistance (‘dirty’ contacts) and subsequently got too hot. The heat wouldn’t have done the diode any good either, so one issue creating another fault. 
My friend replaced the diodes with these - which have the correct connectors to match the loom.
Running fine again now
Russell
