Lucas Rita Question

Question for you Lucas Rita Experts:

Firstly, I am a complete idiot! I left the ignition on, on my Lucas Rita equipped 1974 MKII Commando, for an hour or more. Before my stupid mistake the bike ran fantastic. Now, I have a poor idle with an apparent intermittent miss on one side. Coincidence? Out on the road the bike seems to run fine. So far I have swapped over plugs and leads to see if the issue changes side - no dice. Next I am going to try comparing resistance between coils and maybe swapping them over.

In the meantime I am wondering if leaving a Lucas Rita ignition on can cause problems? I understand most modern electronic ignition systems have automatic protection for the ignition and coils/coils in such circumstances. This is obviously an old Lucas Rita, so I am guessing there is no protection. Therefore I am concerned I have fried one or more coils, and or my trusty Lucas Rita. Not too worried if it is just a bad coil or two, but I really like the Lucas Rita.

Anyway, what do you think?

With ignition on and healthy battery, you can expect that just under 2.5 amps were flowing thru the coils and RITA box. 30 watts with no cooling air. Could get pretty hot.
I would think that if it fried the RITA box it wouldn't function, meaning no spark at all. I would suspect the coils first, but if you determine that it is the RITA electronics, there is a modern replacement available::

The coils suffer first from over heating, hence the later EI's all have auto sleep mode and turn off after a few seconds of not receiving signals.

Try https://www.rexs-speedshop.com/wp-c...Rita-Tips-Testing-Repairs-Rexs-Speed-Shop.pdf
They were very helpful to me when I was trying to sort out a problem with the Rita on my Ducati.

Hi All:

Thank you for your very helpful comments. I finally found the culprit. Unfortunately, it appears I did indeed wound my Lucas Rita black box........

The symptoms were quite odd and perhaps worth preserving for posterity:

For the most part the bike ran reasonably well on the road. It was not down on power and went through the rev range without any problems. It did however sometimes stall at idle, and the idle just was not quite right, like it was slightly out of phase. The interesting / odd bit was the spark plugs became very sooty / black, like the carb mixtures were way too rich. This despite the fact that before the problems started, the plugs were clean as a whistle, if anything perhaps a touch on the lean side. The only other mention I have seen of a similar oddity was noted on a forum by a brit bike owner with a boyer electronic ignition (EI), apparently the issue in his case was caused by a poor ground to the EI.

Anyway, I replaced coils, tested the battery, HT leads, wiring integrity, timing, reluctor to pickup gap, etc etc to no avail. Fortunately, (as it turned out) I resisted the temptation to play with the carb pilot circuit mixtures and main needle jets height.

I was lucky enough to come across a NOS lucas rita box of the correct type. Put it in and now all is well. Spark plugs are busily cleaning themselves and returning to the light tan color seen before my problems started.

I guess I will get in touch with Rex's speed shop over the off season and get the guts of my original Lucas rita tested / replaced.

Thanks again,

James.