spark loss on maiden run

[3potjohn]

Taking advantage of not working AND not raining I decided to give the newly rebuilt 350 motor a run out.On the return leg I lost the front cylinder and had to get back on one.Not ideal for a tight motor.I was cringing. Every traffic light turned red of course.The ignition system has been nothing other than utterly reliable until today. Spark plug was clean,no evidence of soot. I removed the tank and tried swapping red leads/swapping the pickup for a spare/swapping the front transducer. Now i think i have no spark at all.I have not connected a bulb to test the transducers or gone through things any more methodically today but will do tomorrow.Odd though.I only disturbed the pickup on rebuild and the wiring LOOKS ok.

[72degrees]

In my experience losing just one spark is nearly always the pick up - if it isn't just a duff plug, or a bad transducer, or a wiring fault in the green feed to the transducer or the red lead from the pick up. A complete substitution test by swapping everything over is easier if the HT leads both reach OK. At least that's usually possible on a 350, a bit more of a pain on a 250 (unless you make special arrangements).

[3potjohn]

Front transducer-why after 30 odd years does it fail when nursing a new motor....I found in my haste yesterday I'd inadvertenly mis-connected the wiring to the rear transducer,which had been firing ok, thus losing both cylinders,once rectified( i don't think that's a pun) and the replacement fitted it ran like a dream.
I shall still check the old one out with a battery/light bulb method if only to demonstrate it has failed.
If I really get keen i may make a new loom,as i have a spare old one to use as a template.

[Ming]

...-why after 30 odd years does it fail ....

Age gets us all (if we're lucky). At least you have found the problem and fixed it.

[mad muller]

sounds as if you got that engine sorted , did you find the cause of the problem , interested to know the findings when motor was striped down. nice one.

[3potjohn]

I think the big end shells were a bit worn and there was some evidence of a piston having picked up. Actually looking at the piston there is what looks like a small crack,about 4mm in length though it may be a scratch. The left hand main bearing also felt very slightly iffy.One of the gearbox bearning also felt very slightly rough.
Other than that everything looked pretty good. The bike had 48,000km on the clock when i got it,then i put a converter on the speedo cable to switch to miles and it's just hit 70,000 today.

[MickeyMoto]

50k miles before a rebuild?

That sounds good for 70s technology.

[mad muller]

not bad when you think about it , general ware on some engine parts , i doubt lambertini imagined when they left the factory they would be still on the road fourty years later , long live the little vee twins and there owners.

[pedro]

John, "converter on the speedo cable to switch to miles" how does that work and where do you buy such a thing?
Pete

[EVguru]

John, "converter on the speedo cable to switch to miles" how does that work and where do you buy such a thing?
Pete

The default answer to where to buy anything for a Morini is NLM. When they're unable to supply or seem overly expensive, then it's time to ask.

The speedo converter is simply a gearbox with an 8:5 ratio.