Mag spark

[fragged]

hi all

Finally got the mag sparking and it is pretty bright at the spark plug, the only thing that bothers me is the spark
is yellow not blue ?
Bike still won't start so wondering if the spark colour is an indication of anything ?

chhers

[idie]

Very weak spark if it is yellow in colour.

[Spaceman]

It sounds as though you have had problems with the mag - if so, it would be interesting to know what they were?

[idie]

A loss of magnetism can cause a weak spark as well as breakdown of windings and condenser failure. You can get aproblem if the paper isolating gaskets behind the bearing are damaged

[fragged]

Very weak spark if it is yellow in colour.

thats what is confusing me , the spark looks to be very good, not weak at all but just yellow.
But also I am new to Mags.
Originally I had no spark at all so was looking at rewinding it but removed the mag from the bike and spun it up with a drill and it sparks fine,
Put it back in the bike and it sparks well on the kick start.

It has a new looking Lucas metal label on it so seems like it has had some work in the past.

[rhyatt]

I would imagine that you've cleaned and adjusted the contact points, they are .012" gap.
The other important thing is there must not be any suppression in the plug lead , in other words 0 ohms resistance in the plug cap.
Worth checking this.

[fragged]

I would imagine that you've cleaned and adjusted the contact points, they are .012" gap.
The other important thing is there must not be any suppression in the plug lead , in other words 0 ohms resistance in the plug cap.
Worth checking this.

thank you, i will check it all again on sunday. I have some new champion plugs on the way too.
NGK plugs suck on older engines, I do classic mini coopers and if NGK plugs get flooded they never
seem to work well afterwards.

[idie]

No modern plugs will work well if at all once flooded with fuel. Modern plugs have not got a glazed ceramic insulator so excess fuel soaks into the ceramic causing a short. If you want to use Champion look for older ones on Ebay as I do for all my bikes. Look for plugs without the C in the number. Like N5 not N5C. I understand that the company called Brisk are made like old style plugs

[fragged]

thanks for that, I will check out Brisk.
looks like the champions might be wrong then ?

[rhyatt]

A simple test for a suspect plug cap is to unscrew the cap from the lead, wedge the lead between a couple of fins and kick it over.
If you get a better spark with NO cap , there's the issue.
Green spark plug company supply non resistor caps and plugs