1000SP electrics

I have had a 1979 1000SP for many years and have gradually sorted problems as they arise. At last it seems to start OK but is now only running on one cylinder which stays relatively cool while the other gets hot. Fuel gets through OK. The plug is wet when I take it out. I have put in new coils and HT leads, new plugs and a new battery. I have swapped leads and coils round in all combinations but only one cylinder (could be either) has sufficient spark to burn fuel. When I test the plug outside the cylinder there’s a feeble, intermittent spark.
Could it be that the Mistral RITA electronic ignition has finally given up the ghost?
I’m no mechanic and even less of an auto-electrician so I may have missed something obvious.
Any ideas gratefully received.

If one side works OK, then no it hasn’t. If it really had given up the ghost you’ll get sweet naff all. Are the coils wired in series or parallel? If series, should be about 1.5 Ohms each. If parallel, should be 3 Ohms each plus there should be two diodes to feed them. By the way be very careful testing a plug in the open with a Rita, it MUST NOT be operated without a full complement of plugs connected and working. PS (edit): have you tried new plug caps, or swapping them over.
Mike H2014-09-05 16:44:31

Faulty plug? Failing under compression.
TIP: I have two crocodile clips joined by a hefty piece of wire which I attach to the plug and a good earth (as opposed to a bad one ) to avoid damaging ignition components.
This is well worth a look
Guzzi electrics
Best of luck
Steveguzzibrat2014-09-05 19:50:56

Have you checked your timing, one could be way off the mark.Where abouts are you? This sort of thing is impossible to diagnose by 20 questions.

It's a Rita.  One side works so we have to assume it isn't that. Also I take it both sides worked before this. (?)
Yes could be, good mention. Swapping plugs will prove or disprove that.

It sounds like from what you are saying the problem is swapping from left to right at some time in your tests. Don’t trust new parts, they can be faulty. What did you swap to make the fault change from one side to the other?Do you get a good spark on one and poor on the other or are they both poor?

At the risk of elderly female relative & eggs situation. A couple of basics you may or may not have thought of.1. In my experience Lucas Ritas are very reliable but if they fail they tend to fail completely. Never heard of one breaking down on one side.2. As stated earlier new electrical components are often faulty, make sure the items you are substituting actually work properly.3. If you haven’t already, swap the components (coil, lead, cap & plug) from the working side to the none working one. If the non working side now works your problem is one of the previously listed components. Replace them with new working items ( i would change the lot, its not expensive) job done.4. I’m sure you know this anyway but worth mentioning. Lucas Rita uses 6v coils so don’t replace with 12v.Sorry if this is a bit basic. Hope it helps.

The Lucas Rita on my Lario / Targa hybrid uses 12V coils surprisingly so check what is correct for your system.As for the reliability of replacement parts, Italian Motor and one other has had this recently with replacement condensors, took him ages to realise one of the new ones was a dud.

Just thought of something.    Rita amplifier must have a good earth, so check your frame connection.    Also, these Rita's and getting quite old now, and on mine, the 5-pin plug/socket in its loom got very tarnished/cruddy looking connectors, so-much-so that last year (during the rewire) I decided to cut it off altogether and solder on new wire extensions, and thereby remove one possible source of bad connector trouble.   Amplifer earth also goes through this connector.    Plus ~ check the gap between [BOTH] rotor ridges and the pick-up pole piece hasn't moved for some reason, if gap is too big pick-up signal may be weak.    HTH

Thank you all, fantastic response. I haven’t been able to get in the garage for a bit but will check out all advice. The new bits were 2 x 6v coils wired in series, HT leads, plug caps and plugs.

Tim B