MOPED ARMY

Ron,you're a pretty fair mechanic from what I've seen so don't let me insult you here,but I've seen bad coils do this exact thing.You probably already know that coils lose their `umph' with heat and this heat is created by the windings when they are activated to step-up the voltage.Usually it's the coil which fails like this and not the condenser because condensers tend to cause some backfiring or just go dead all at once. Hope it's this simple! BYE!

Don,

No offence taken, if I did not want sugestions I would not ask.

I had allready decided that I had only the magneto coil, ignition coil, condensor and wiring left to look at. What I was hoping was that someone had seen these same symptoms.

What really bothered me was the cycle time of the problem, 15 mins on, 15 mins off. I would have though that once I got something hot enough to fail, it would fail again quickly the second time.

Anyway, read my other post for an update.

Ron

Thanks to Don and Mike for the suggestions. The coil seens to have the vote for "most likely to fail".

I took the flywheel off yesterday to eyeball everything and make some resistance measurements. The magneto coil and ignition coil both had reasonable resistance readings. One ohm or less for the mag coil and ignition primary, 5K ohms for the coil secondary.

Then I found the condensor! Most of you will not find this exiting, but the last time I had the flywheel off to check the points on my other ped, I had not seen a condensor. Well, in typical french fashion, the condensor was mounted on the back side of the magneto, out in all the crud from road and engine, with a wire running through the plate to the coil.

The next most exiting thing was that the condensor read 5k ohms resistance. Still had a kick (some capacitance), but it should not conduct DC power.

The next, almost heart stopping event, was visiting themopedjunkyard.com, and realising that a 19.95 part + 5.00 handling + 3.50 shipping leaves me close to $30.00 out of pocket!

It is true, that in typical french fashion, the condensor is a mechanical work of art, however, where it mounts, you can't even see it.

Anyway, I have decided that the motorcycle condensor in my random parts will do, the question is, how to mount it.

Then (imagine sound of dope slap, open palm against forehead), it occured to me that I could mount the condensor next to the coil, make a short adaptor to allow the condensor to connect between the points wire and the coil. As an added feature, the condensor will now be up on the frame, away from the engine and road grime.

More to follow.

Ron

It worked, made it to breakfast, the brewery and home again. I guess the condensor was the culprit.

Ron

Don,

Fred mentioned in one of his past posts that moped coils very rarely fail. I think I agreed at the time as I have never had a coil on any motorcycle fail.

I suppose a plastic one could crack or a steel case could rust through and cause failure, but I have never seen it.

I have replaced a few auto coils, I suspect that living under the hood where it is hot and providing 4 - 8 sparks per rev may increase the failure rate.

Ron

Don,

You should have mentioned to your mechanic that the condensor read 5k ohms instead of infinity. I have taken the same 40 mile ride as I did before I fixed it with no failure. On the previous ride it failed 5 times.

I don't know about lawn mowers but they may suffer from the same environmental conditions as cars, or maybe they are more cheaply made, or maybe it was really the plug wire that failed as they are usually monolithic.

Ron

Don,

I took the liberty of pasting your email in here ahead of my response because it confused me and maybe someone will enjoy your puzzle.

My confusion here is that in my previous post, I wondered if your mechanic would still think my coil was bad, even though my condensor read 5 K ohms, proving that it was bad. I don't recall ever mentioning that condensors rarely fail. In fact, even though I have not seen too many failures, I would assume that they are failure prone, or why would points and condensor normally come together in a tune up kit?

>Let me give you an example of a

>rarity.Problem yesterday: Moped doesn't start.Spark

>plug has very weak spark.The diagnosis normally would

>be pretty easy,right? Not in this case,at least not

>for me.Care to take a stab at it? I solved it

>yesterday by removing the spark plug.The clue is

>`noise',so you don't think I am making this up.Another

>hint is : these don't fail very often either. BYE!

Without the clue, I would have to suspect anything and everything in the ignition circuit, from the magnets in the flywheel to the plug. Given that the clue is "noise", I have to guess you mean RF noise and the plug suppressor cap was bad. I am not sure how you solved it by removing the spark plug, my ped won't run worth a hoot without one.

Ron

Don,

No argument from me, I guess my original point was that if your mechanic had been told that my condensor was leaky, it would most likely have changed his diagnosis and his prediction that the problem would recur.

I still agree with Fred on the coil. I think that coils are often replaced because they are difficult to diagnose without a good understanding of how they work and how to test them.

In any case, given a choice between a condensor and a coil, if I had no way of testing either one, I would allways try a new condensor first because almost any ignition condensor will work, at least until the points burn, so a substitute test is easy, and coils are much more specific and expensive.

On the other hand, I never assume that a coil will never fail, as you can see from Ree's latest posts.

In case anyone is holding thier breath waiting for the answer to your puzzler, here is a copy of your email to me:

Hi,Ron! No, your thinking too hard.It's a `down to

earth,run of the mill noise.I'm just mentioning it

because I was so surprised at the problem.Here's what

happened.I went out to take a long planned moped

excursion(over 60 miles)and when I tried to fire it

up,I couldn't get it to go.I checked for spark and it

was really weak.Now i'm like you,thinking

;Wire,coil,spark plug,points,etc.,when I decide to

crank it really hard by pedaling fast .I heard this

crazy noise like the `Wheel of Fortune'game show has

as the `clicker-pointer'strikes the pegs as the wheel

is rotated.I kept pedaling,put my ear down closer,and

the noise was coming from the horn! It turned out that

the switch failed closed and it drew so much current

that the total magneto charge wouldn't create enough

spark.How's that for strange? So,everybody out there

who has a weak spark should check for a current bleed

off also.This bike has a horn which really draws a lot

of current.I'm wondering if maybe age is getting the

better of it,but it works fine.Just thought I'd share

this weird little occurrence with you guys.BYE!

I have to admit that this is a wierd one. Normally, the horn would run from a completely different winding than the ignition. Are you able to find this connection on the wiring diagram, or is it possibly a short in the wiring?

My Motobecanes blow the horn if the run stop switch is in the stop position, but that is because it closes the horn contacts at the same time as it grounds the ignition (they are both on the same switch). If you try to start it, it quacks to let you know that the ignition is off. The down side is that when you turn the switch off the horn makes a noise like a duck being choked.

Ron

Now wait a minute ,Ron! You haven't been strangling ducks again have you? And I had pictured you as a mild-mannered problem solver who would treat one duck the same as the next one,with no prejudice! The only way you're going to get out from under P.E.T.A.(PEOPLE EATING TASTY ANIMALS)on this one is to admit that you bought that #1 selling tape `DUCK-CHUCKING WITH STYLE AND GRACE' . Just thought I'd try to help you get outta' this mess! BYE!