MRC Forum- brought to you by www.morini-riders-club.com

I renewed the ignition transducers about 5 years ago but hardly do a thousand miles a year and recently it has started running on one cylinder when hot....or after half to three quarters of an hour. After leaving it to cool down for an hour or so it starts and runs fine again. Any suggestions please? I don't really want to go delving into it and start buying new parts etc unless I have a clear idea what the problem might be

eekzoids wrote:I renewed the ignition transducers about 5 years ago but hardly do a thousand miles a year and recently it has started running on one cylinder when hot....or after half to three quarters of an hour. After leaving it to cool down for an hour or so it starts and runs fine again. Any suggestions please? I don't really want to go delving into it and start buying new parts etc unless I have a clear idea what the problem might be

Start by checking for a spark on the non-firing cylinder when hot. If not, then swap over the transducers and see if that transfers the problem to the other pot - in which case its a transducer issue. If it doesn't then, without attempting a start (both plugs out) try swapping the pickup leads only. If that transfers the lack of spark then its the pickup. It sounds like the stator winding is OK, so my *guess* would be a pickup with a crack that opens up when hot. Remember to put the pickup leads back to the correct transducer after this test!

Otherwise (good spark on both cylinders when hot) I it could be too rich on the carb on that pot -perhaps a leaky seal on the starter jet plunger on that one.

Thanks for that wonderfully detailed reply. I'll have a go at that in the next few days and let you know how I get on.
Cheers

I had a similar recurring problem - but it occurred much sooner -after about 7 miles ( almost exactly each time) and again resolved itself when cool. -in this case it was the stator that needed rewiring - as I remember it's resistance measured fine when cold and I spent a lot of time swapping components to no avail - once I bit the bullet and got it rewound problem solved - hope you get it sorted -Duncan

I've certainly had stator ignition windings that give up when hot on Morinis and other bikes with similar systems, but in my experience that usually takes out both sparks on a Morini. Certainly worth checking the resistance hot and cold though as it is indeed the 'heart' of the system. I agree that it's probably best and easier to start with that diagnosis (and checking stator output voltage when running) before moving to 'swapping'.

As one coil appears to work, swap the feed from the magneto to the other coil and run the link cable across.

If it still misfires on the same cylinder I would suggest the magneto is not at fault. I would have thought the bike would stop altogether if the magneto was dodgy. Then again, electrickery is the work of the devil!