Topic: Motor stranded, sparks on the coils

[jacquesleclochard]

Well, it took me three hours to ride the 20 miles to the outskirts of Amsterdam - and there, it died.

At first I thought it was a carb problem; stuttering. I rebuilt the carbs but didn't synch them. Maybe the mixture was off?
But after a while it REALLY started running irractic. Stuttering, then dying, then slowly getting back to speed.
After a while, the cylinders dropped. So I figured it was the ignition. That's electric and I didn't tamper with it.
Maybe the spark plugs? If the mixture was off, maybe it didn't ignite and overfouled?

So I walked into the first gas station I could find, took off the carbs and hitched a ride home.
The next morning I get back there, with cleaned carbs and a plug socket. Nothing. Turning, but not firing up.
Battery died. I hook the battery to a car and recharged. Took out the plugs. Little sooty, nothing too extreme. Spark, yet small.

After taking a closer look at the coils, I notice that when I hit the starter, it sparks! The coil sparks on the outside. Both coils. Is that the gremlin?

I suppose this isn't normal, is it?

[dave500]

no,its not normal,i think it may have been mentioned by me once or twice or thrice that carbys have been taken apart over and again only to result in the fault being ignition,bummer being stuck out on the road aswell,where exactly is the spark?

[dave500]

three hours to go 20 miles?i couldnt stand that #$%* man,dont you guys split lanes,,or are you snowed out?

[jacquesleclochard]

Oh, no, it usually takes me 20 minutes or so. But it was the engine that was really bogging down. The problem is bad!

The sparks spark at the rear side of the coil, above the connectors. Could bad insulation be the culprit? I bought these coils aftermarket, a little over a year ago? In the meantime I did have a motorcycle crash. The tank was dent, maybe the coils took a beating as well?

[dave500]

if the coils dont look physicaly damaged id suspect just #$%*ty cheap aftermarket coils have blown the internal insulation,,so its sparking from within the coil to the rear,,like to the blue and or yellow wires?umm?id try new coils judging by your description,can you maybe with some plastic insulate that area just to get the bike home?,,man 20 miles,,in how many hours?i feel sick,,,,,

[jacquesleclochard]

Dave, it was horrible. An adventure on a dying horse: "C'mon boy, just a little more!"

[Spanner 1]

Unscrew each plug cap and trim each wire back a few mm. Look in the screw end of each cap and clean out any bits of rubber in there... put 'em back on and try and start bike again..... Daaaaag .

[jacquesleclochard]

Already done that the day before it bogged down. So I doubt that's it. Plug caps aren't much older than one year, either.

[grcamna2]

if the coils dont look physicaly damaged id suspect just #$%*ty cheap aftermarket coils have blown the internal insulation,,so its sparking from within the coil to the rear,,like to the blue and or yellow wires?umm?id try new coils judging by your description,can you maybe with some plastic insulate that area just to get the bike home?,,man 20 miles,,in how many hours?i feel sick,,,,,

+1...I'm with what dave said.

[phil71]

Check the main ground

[TwoTired]

The description sounds like the spark plugs were fouling and finally got bad enough to quit entirely.
Doesn't mater how bad (or good) the ignition is, if the plug electrodes are shorted/grounded, then engine isn't going to run.

Pretty simple to pull out a plug or two and look at them.  I've had clogged air filters enrich the mixture enough to soot up spark plugs and the power degradation was as you described.  I'll functioning carbs could do the same thing (floats too high, bored out jets, dirty emulsion tubes, improper settings. etc.)

Cheers,

[jacquesleclochard]

Hey TT, tx for stopping by. I took out the plugs, cleaned them. They looked foul, dark, but not pitchblack. One even came out with a slight tan.

I might add that this surprised me, since I rode a few miles WITHOUT an air filter; I did that to see if it were the air passages in my carbs that got clogged.

After cleaning, I checked them all for spark - however weak (it only jumped a gap no wider than a millimeter) they worked.

I should add, that I reset the float height, the needle clip position (it was on the 2nd clip instead of the 4th, counted from the bottom up on '75 K2 model carbs), all back to original settings the night before.

Back to that spark on the outside of both coils, because this really concerns me. I can't imagine it is supposed to do that. Normally I don't look at the coils when my starter is turning.

Is there anyone with a similar experience? I'll pick up the bike tomorrow - if it's still there (knock on wood) - and swap the coils and plugs first off. Carbs are going for a ultrasonic cleaning. I want to get this gremlin out.

[bjatwood]

Put some silicon caulk on the wire where it is sparking. Let the caulk sit up a hour or two, clean the plugs up while you wait for the caulk to. Fire it up and ride it like you stole it back home! And, if your riding your bike and problems come up, turn around and head back home. The walk is much shorter that way 

[phil71]

If I'm reading this right, the coils are arcing to the frame? It seems incredibly unlikely that 2 coils and 4 leads would all fail at once. I've experienced a situation where a coil, that wasn't firmly grounded, sent the spark out of the steel around it's mounting bolt. The high tension side of the coil doesn't care where it leaves the coil, and will always take the shortest route. I'd be looking for whatever is common to the two coils, which is mostly the 12v+ and their grounding.

[TwoTired]

Hey TT, tx for stopping by. I took out the plugs, cleaned them. They looked foul, dark, but not pitchblack. One even came out with a slight tan.

Sounds like plug fouling isn't the issue here.  However, it IS important to check plugs for two things. 1) no bridges between electrodes.  And, 2) there is at least more than distance than the electrode gap of white showing on the center electrode insulator.

Back to that spark on the outside of both coils, because this really concerns me. I can't imagine it is supposed to do that.

No, it shouldn't.  Spark energy will take the least resistive path.  Something, is allowing it to take a shortcut rather than go out to the spark electrodes.  Certainly there is a break in the insulation there.   And, perhaps there are conductor breaks between the coils and spark plugs.

FYI: The coils don't need to be frame grounded for electrical purposes (cooling is another matter).  However, the coil secondary does use the engine (connected to frame) for part of the conduction path between spark plugs.  Doing so, of course, raises the potential throughout the entire conductor body.  And if the path becomes easier, routes wherever the lowest resistance is.

Cheers,

[jacquesleclochard]

Update: I managed to get the bike back home by van. Didn't bother starting her up; it's storming like mad outside.
Whenever I find the time, I will take off the coils and test them before replacing the aftermarket ones with a set of NOS.

[Kong]

I don't see what the mystery is here, you've got two bad coils.  Go get two good ones.  No short or lack of ground is going to cause arcing across the surface of the coil, the only thing that will do that on an old Honda-4 coil (the coil and the ignition wires are of one piece) is a break in the ignition wire part of it or a crack in the case above the channel the wire resides in.  You can fix it with a dremel tool but its a lot more trouble than its worth, just get a set of good aftermarket coils - ones that use separate plug wires.

[grcamna2]

Update: I managed to get the bike back home by van. Didn't bother starting her up; it's storming like mad outside.
Whenever I find the time, I will take off the coils and test them before replacing the aftermarket ones with a set of NOS.

+1 on a set of good O.E. coils from Honda.