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weak/intermitant spark

Posted: Tue Apr 13, 2010 9:12 pm
by dave wheeler
rebuilt a series 1 with gp bits i had lying round, bike sometimes runs for a few seconds then dies, plug wet, green wire off stator giving weak/ intermittant spark, points (new) seem to be working ok, any ideas. who does flywheel re-magnitising, could it be this?
cheers
dave

Re: weak/intermitant spark

Posted: Tue Apr 13, 2010 9:18 pm
by byron
check the wire to the condensor, or replace the condensor with a known good one.

Re: weak/intermitant spark

Posted: Tue Apr 13, 2010 9:22 pm
by sean brady scooters
yes ,try a new condensor...

Re: weak/intermitant spark

Posted: Tue Apr 13, 2010 9:23 pm
by J1MS
If you have a multimeter, then set it on Ohms and check the resistance on the green wire from the stator with points open and shut.

And Yes if the flywheel needs re magnetizing it could cause ignition faults, but would normally result in poor lights first.

The condensor is also a good possible cause.

Re: weak/intermitant spark

Posted: Wed Apr 14, 2010 11:34 am
by dapper
Also check you don't have any dry soldered joints, and that the little insulation plastic washers between the points are seated correctly (as shown in Sticky's bible).

Re: weak/intermitant spark

Posted: Wed Apr 14, 2010 1:11 pm
by firekdp
Make sure that the points are cleaned of any protective coating, as the points not contacting will result in a weak spark.
The easiest way to test it would be with a battery and lamp circuit as used for testing when the points open during timing. Connect between green and earth and rotate the flywheel slowly. With the points closed the lamp should be bright, when the points open it will dim slightly.

Re: weak/intermitant spark

Posted: Wed Apr 14, 2010 4:03 pm
by soulsurfer
What would/could cause a weak spark on a 12 volt electronic system?

Re: weak/intermitant spark

Posted: Wed Apr 14, 2010 7:05 pm
by J1MS
On the stators I've fixed it's usually the LT coil or the earth from it.
On the scooters I've fixed, if it's not the stator it's most times a poor earth to the coil/frame to engine. That's mostly the problem IMO. But there will be other reasons like magnets, faulty ignition Switch or CDI and other causes.

Re: weak/intermitant spark

Posted: Wed Apr 14, 2010 9:54 pm
by dave wheeler
thanks guys, the points and condenser are brand new, how can you tell if a condenser is good?, how can you tell if the magnitism is good or poor and who could i send it to to get re-magnitised
many thanks
dave

Re: weak/intermitant spark

Posted: Wed Apr 14, 2010 10:00 pm
by Andy Pickering
Anychance of loaning a flywheel to try..?, bit expensive to send off if thats not the problem..