Topic: sparking at the points when they ground-no juice to 1-4

[CapeCafe]

I have a 76 CB550 that was running fine to day until it just started missing after about 10 miles.  I pulled over and could tell I was not getting and spark to 1-4.  The pipes were much cooler than 2-3.  When I pulled the plug it looked as if the spark plug gap had doubled in size and I was not getting any spark to the plug when set against the engine. I pulled the points cover to see check and when the bike was running the 1-4 points had a noticeable spark when they were closing and the 2-3 side had no spark when closing.  I don't think there should be arcing at when the points close; is that right?  Any ideas as to what causes it?  When I searched the forum I saw a couple references to a closed condenser; even though its new, could that be the problem?

The wiring is correct with all new connectors, plugs, points and condensors, and was running strong until 1-4 just shut down this afternoon.  I'll pull the 2-3 plugs and check the gap tomorrow.  I gapped the plugs and points correctly when I put them in (> 150 miles) and the timing was spot on.  When I checked them on the road, the 1-4 plugs looked as if the electrode had shrunk the gap was so huge, and they were a light mocha brown color.  I have stock coils, plug wires and caps.  Everything tested and performed as designed when I completed the build a couple weeks ago.  Any thoughts appreciated.

[Thousandson]

A light brown, or a little yellow sounds like spark is really hot. What kind of plugs are you using? I'm using KNT? copper heads. I stuck with the copper heads, just because of old school wiring, and old coils. Keep me posted.

Looking at my manual,
Over heating:
-identified by a white or light gray insulator with small black or gray brown spots and with bluish-burnt appearance of electrode
-Caused by engine overheating, wrong fuel type, lose spark plugs, too hot plug, or incorrect ignition timing

[Xnavylfr]

If you are getting sparks  at the points, check and make sure they are clean and have proper gaps!!



Xnavylfr(CHUCK)

[CapeCafe]

I'll have a chance to check the points gap later this afternoon to see if they did slip open.  I set them about 2 weeks ago, but was having a problem getting the voltage to pass through the points when they closed because I had the condenser clip grounding out on the points plate.  I fixed it and until yesterday afternoon everything was working fine.  The plug gap increase on 1-4 cylinders is the interesting thing to me.  What would cause the electrode to shrink/melt?  I understand letting the bike run lean would increase the heat, but can it get hot enough to still run well from 1,200 rpm to 9,000 rpm with no problems to melting to the point the spark can't gap?

[pedro bighead]

just went thru this. had to take the whole timing assembly off and clean it all up. Then took some emery cloth and cleaned the advance shaft so the surface was shiny smooth. put it back on and tightened everything up. now the shaft surface and the point end with the plastic rider on it moves much more smoothly. Once i did that and set the point gap exactly the arcing went away and haven't seen it since.

the point gap is critical, use a minuscule amount of dialectic grease on the shaft but only enough to make it slide, too much shoots out and fouls the points, even brand new ones (points) work better when dressed with an emery board.

hope this helps.

M

[CapeCafe]

I just checked and the plugs are all gapped at 0.025".  The points are at .015" and cleaned with 600 paper (there was a slight discoloration from the arcing).  I have checked:

12 volts through the blk/wh wire when ignition and stop  "ON" - check
Continuity through the coil - blue thru to blk/wht -  check
12 volts through 2-3 points set when open - check
12 volts through 1-4 points set when open - NO

I tried an old (but functioning condenser) on the 1-4 side with no difference.  The arcing I was seeing at the 1-4 point set when running is no longer there.  Any thoughts on additional trouble shooting tests to figure out why I'm not getting power through the 1-4 point set?

[CapeCafe]

I found out that the problem was being caused by a bad condenser.  After going back over the wiring I had voltage through the points but they were still arcing like crazy.  I tried a 3rd "old" condenser I had in my tool chest and it fired right up on all 4 cylinders, smooth as silk with no arcing at the points.  The one I replaced was new with less than 130 miles on it.  Is there a way to wreck a condenser (besides smashing the #&*t out of it)?

[pedro bighead]

a lot come pre wrecked, you proved that by replacing the pre wrecked ones with a functional one.

I have gone thru a number of them so far just trying to get the bike running.

[TwoTired]

Not a good idea to use any abrasives on the point contacts.  They all leave behind some of their grit and it embeds into the soft contact material.  The grit particles are an insulator and thereby reduce current handling capacity by reducing contact area.  They also wear off at a different rate, leaving the actual conductive material in a valley, also increasing resistance heating.  The effect lasting is increased heat on the contacts and much faster wear during use.  A point file, on the other hand, uses a cutting material that is far harder and very little to none embeds into the soft contact material.  The only "grit" it might leave behind is the small particles removed from the contacts which naturally have the same electrical properties.  Following a file, a points burnishing tool will polish up and flatten the surface for increased longevity and for accurate gap setting.