coil question

Jon Dalton /

has anyone ever had a problem that turned out to be the coil? it seems to be the consensus here that it's never the coil. since my moped left me stranded in toronto i took the points off, filed them real good, made sure there was voltage coming from the magneto and set the timing bang-on with a volt meter. I put it together and there was a kick-butt spark at first, but then i put the plug in and ran it and it ran like garbage. i checked the spark again and it sucked this time. then i tried switching to a brand new plug, no difference and now the spark is almost nonexistent. The condenser is new but it's a lawn mower one and the points seem to work fine based on checking them with the volt meter so what else could be wrong? the wiring is fine, there's no kill switch or anything just an ignition wire going straight to the coil. anyhow i did order new points and a condenser for this moped specifically as those parts are available. the coil is a lot harder to come by so i would have make whatever i get my hands on fit. my friend said when i described the symptoms, the first thing he said was a weak coil. i didn't believe him at first but now it seems like it's the only thing left to fix. what usually happens when a coil is bad. would the moped be running fine one day and then all of a sudden crap out on you?

Re: coil question

Ron Brown /

Jon,

The rest of the references to coil diagnosis on this site always say to substitute a known good coil or try the "bad" coil in a known good ped.

Anyway, your symptoms could be a coil, they could also be a bad connection almost anywhere in the ignition circuit. Especially check the plug cap resistance and connection to the coil wire. Also, mal\ke sure there is no place on the HT side where you could be leaking to ground.

Good luck,

Ron

Re: coil question

Chris Robertson /

What kind of moped do you have?

Re: coil question

Chris Robertson /

Similar to coils, I doubt that plugging in a condenser from another (different model) engine will work. Condensers are capacitors, they come rated to handle different voltages and their capacitances (measured in Farads) can vary greatly from engine to engine.

When your OEM parts come in, you might find that your problem was the condenser after all.

Have you replaced any other ignition system components with substitutes?

If you tell us what kind of moped you have, someone might have a spare coil for sale.

Chris.

Re: coil question

Jon Dalton /

I didn't know what a condenser actually was but now I do. I know what a capacitor is and what farads are because i just took electrical physics. I also know about coils and inductance but I didn't know the magneto coils were supposed to have next to no resistance in them. I figured with all that wire, they must have some, and that led me to un-wind the entire coil because I thought it was bad when it really wasn't. The points were sparking at higher rpm's and that led me to believe the condenser was shot. The moped is a 1969 Honda PC-50 and parts for those are hard to come by. I see several of these mopeds in the buy/sell papers but they are always in mint condition and the guy is always asking way too much. Mine was different. I literally rescued it from the scrap metal pile. My friend said if I find the specs on that coil that we could wind a coil ourselves. With the voltage needed to jump the spark plug, I'd think that would take a lot of wire and a lot of time.

Re: coil question

Chris Robertson /

Hi Jon!

PC50s are really nice mopeds. I bid on one last year, but didn't win. I can understand why you are having such a hard time to finding parts!

I guess the only advice I can give you is to contact the people you see selling "mint condition" PC50s and ask them if they have extra parts.

<a href="http://www.avweb.com/articles/magcheck/">Magneto Intro</a><br>

<a href="http://www.users.globalnet.co.uk/~pattle/nacc/arc0080.htm">Info about PC50 restoration</a><br>

Good luck!

Chris.

Re: coil question

Reeperette /

Ho, John...Tell me what the bikes electrical system main voltage is, and what spark plug heat range it uses, and I can maybe tell you what other mopeds coil would be next closest....coils are prettymuch a per-'ped issue, as Chris stated, so no guarantees there - but it's also fairly plausible that Honda might have used a lot of the same electrical parts on more than one model of moped for continuity and ease of replacement issues...far as I know, most Puch electrical parts cross over, so why not Honda ?

Anyhow, lemme know that Main Voltage and Spark Plug type/heat range, and we will see.

-Ree

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