Points arcing

[BooG]

Whilst cranking, I have noticed that there is some arcing away from the contacts themselves. I'm sure this is not supposed to occur. There is a new dyna coil installed, new points and a condenser. The carbs had a complete strip down, ultrasonic clean and re-build. Compression is good on both sides. What should one see inside the bean can under "normal" conditions? [smiley=uhoh2.gif]

[Ed Miller]

Where is the arcing happening if not at the contacts?  That does sound weird.  For points, all I expect to see is faint arcing at the point contacts when they open, hard to see in good light.  

[Barry]

There will be some arcing across the points contacts even when the condenser is good ( mine do) and much more arcing when the condenser is faulty. Hard to quantify this in words unless you already know what it looks like when the condenser is good. The spark at the plugs will be very weak and orange if the condenser is faulty. If the spark at the plugs is strong and more blue than orange I wouldn't worry.

There should not be arcing anywhere else inside the bean can.

[Justin B.]

Also, maybe the Dyna draws a bit more current than the stocker...

[nhmaf]

You might have insulation on a wire that is cracked or failing and in need of replacement.  Other wise, the only arcing one should see is at the points gap when they copen (And at the spark plug electrodes, of course).

[Rob Valdez 79 R65]

As long as the points are not pitting real fast, you are O.K.  

And as long as the arc is confined to the space between the points, as the others have inferred, that is O.K.

I'm pretty sure it is normal and they are supposed to?  (could be wrong!)

[Barry]

If we think about it the points are switching upto 5A at approx. 300V so they always do arc a little even when everything is OK.  If they didn't they would never pit and last forever.

[darrylri]

The older bikes with magneto ignition are much easier on points because they are switching the low tension side of the circuit.  They really do last almost forever.

However, if you see more than a small bit of arcing across the points, even on a Kettering* ignition bike, then probably your condenser is dead.  Even if it's brand new, try another one.

*)That is to say, battery/coil system.

[Bob_Roller]

A simple test to check a condenser, is to remove the wire that goes to the points, and then connect a multimeter to to it, the red lead to the wire on the condenser, the other black lead to the condenser case, with the meter set to the ohms scale, you should see the resistance rise with time, as the condenser 'charges, if the condenser is still good .

[MrRiden]

Whilst cranking, I have noticed that there is some arcing away from the contacts themselves.

Arcing at the point contacts is to be expected. The condenser [capacitor] is there to limit the arcing and extend the life of the points. Arcing in a location away from the points, if I understand you correctly, should not occur and would indicate something is amiss.

[Barry]

Boo

Bob's test works I did mine that way. The rise time is quite quick and maybe difficult to interpret if your not used to it and If you do several tests, and who wouldn't, be sure to discharge the condenser between tests by shorting it out or you won't see the condenser charge after the first attempt. I find analogue meters are easier to interpret than digital for this test

As the problem is to know how much arcing at the points is normal another test that you could do is remove the condenser and see if the the arcing increases substantially.  If it does your condenser is probably OK if it doesn't then it was faulty.

Trouble is that's easier said than done as the spade connector link to the points inside the bean can is part of the condenser assembly.  You would have to improvise either by removing the condenser and making up a straight through connection or by making sure the case of the condenser is not earthed.