weak intermitant spark

andyp · Post by **andyp** » 31 Jul 2009 09:12

hello chaps, hope someone will be able to help here,thought i was coming to the end of a 14 month restoration, 78 strada, have to say bike looks fantastic but when i kick it over only seem to get a weak iregular spark, most things on the bike have been either renewed or reconditioned including stator rewound, flywheel re magnetised, new regulator/rectifier, wiring cleaned, repaired, new nlm pickup, new transducers/cdi unit, engine rebuilt, new spark plugs, had this w/e down for a possible mot but have to say having spent the last 14 months and considerable expense i'm almost ready to take it down to nlm and say sort it. That would be a shame having come so far to be beaten at this stage. i know there are some very knowlegable morini boffins out there so any ideas would be great.

cheers, Andy.

boris tarpit · Post by **boris tarpit** » 31 Jul 2009 10:27

If everything has been renewed like you say it must be some mis-match between components maybe. . ?? I can't imagine it's a wiring fault.. . Have you checked the stator resistance?? Was the rewind done with the correct guage wire?? Is the spark weak on both cylinders or is it better on one?? Have you tried bypassing the ignition switch??. . .

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andyp · Post by **andyp** » 31 Jul 2009 13:43

stator was rewound at nlm, reading about 200ish ohm but thats with a cheap multi meter, have tried bypassing ignition, apparently the spark given with these new pickups/transducers/cdi's is weak anyway but this is hardly sparking at all.

robinh44 · Post by **robinh44** » 31 Jul 2009 18:20

Andy

Have you checked the spark strength, you can make a spark gauge from an old spark plug and cut down the side so you can create a gap between the overhead and centre electrode. Start with a gap of 5mm and see if the spark can jump that. Also check the spark plug type and plug cap type as if they are both resistive types this can reduce the spark strength. The plug if ngk will have an R somewhere in its code. Also measure the stator ignition coil again and get a precise value, best to use a digital meter. Boris suggestion of bypassing ignition switch is a good one as you could have a slight resistance to earth if the ignition switch is a bit tired. Let us know how its going.

Robin

andyp · Post by **andyp** » 31 Jul 2009 18:38

thanks robin, got myself a digital meter today, gonna have another go at it tomorrow, will keep you posted.

Andy.

3potjohn · Post by **3potjohn** » 01 Aug 2009 06:23

Verify that resistance on the green wire from the generator. If its <200 say around 185 that will be low for a newly rewound unit. Have you tried to bump start it? My coil got rewound and is now nearer 300 ohms but was 185 when I got the bike (measured on my Aldi multimeter.) It would run but not start easily on kick or electric foot but I live on a hill.....
Spark was a bit feeble. Actually I fitted the rewound unit and away I went. I have never checked the spark quality since to see the improvement.

ringer · Post by **ringer** » 06 Aug 2009 16:46

What state is your battery in? I know that the way the system works, this shouldn't affect the starting, but I find that when my battery is low on charge the bike is a pig to start. Recharging the battery overnight seems to cure that.

Derek Wright · Post by **Derek Wright** » 09 Aug 2009 21:51

Andy,
I know you said you tried bypassing the ignition switch, but for what its worth, I had an ignition switch issue a couple of months ago with my x Kanguro. Arrived home one Thursday evening, parked up, no problems that day, following Monday morning, going to work, would'nt start, usually 3 kicks max. Eventually gave up and got the X3 out ( luxury!! of 2 Kanguro's on the road). Anyway after a few days, had a look at the X, weak spark then nothing, so left it again. Thinking, this is crazy, bike running fine then suddenly no spark. Tried again, noticed initially, there was a spark then it seemed to become intermittent, decided to give the switch a few flicks, and lo and behold the spark came back, quickly put the plugs back, few more flicks and away she went , first kick. Now once a week or so, a few extra on off flicks of the switch, no more problems.Must have been some corrosion on the switch contacts.
Might be worth a try, particularly as you bike has been laid up for so long.
Might be worth a try.
Derek

andyp · Post by **andyp** » 13 Aug 2009 14:12

ok fella's, think the problem might be solved, sent the new transducers,pickup,rewound alternater, re magnetized flywheel back to alex at nlm to test it out on their bench, he reckoned he got a spark out of it at around 1500 rpm, he tried a diffrerent pickup and that seemed to cure the problem. just received the whole lot back today so will refit and try an fire it up this w/e.

EVguru · Post by **EVguru** » 14 Aug 2009 08:54

NLM did have some issues with their new pickup assembly.

The manufacturere of the pickup coils changed the specification. Not a problem for most ignitions, but on the Morini where the voltage level is used to control the advance it was.

I can't remember if NLM used another supplier, or a different pickup coil, but they apparently solved the problem.

andyp · Post by **andyp** » 15 Aug 2009 09:53

hello paul, everything back on the bike and a nice strong spark so the problem was a faulty pickup, think it was just a one off and not a faulty batch so the next problem is i think carbs. tried to kick the bike over and not a murmour, theyre replacement carbs from nlm as the originals were knackered internally once they were ultrasonically cleaned. The replacements also cleaned. I'm getting fuel through into the float bowls but the plugs seem dry, as an aside ive got a 2-1 exhaust and alex at nlm suggests 260u atomiser 42 main and...........not sure what idle jet but ive got what he suggests, just not fitted them yet. at this moment in time i just want to see if i can get it started with a standard set up, so......could you throw some light on float heights and also which way the slides are fitted in each carb. i know the site has a link to setting up carbs which i'll use but any advice/tips from yourself would be greatly appreciated.

cheers, Andy.