Spark Troubles (WARNING.. its quite.. long)

Jared
Jared

June 18th, 2005, 4:09 am #1

Here's my story. I acquired a 77-8 Honda Express (unsure of exact year). This moped did once run a while back but since it has been neglected etc. So I go at it. I clean everything on the outside. Scraping sludge off the block etc. Unfortunately when I got it, it didn’t have a coil or sparkplug. So I poke around and find a coil on EBay for a decent price and got it. I bring it back home and hook it up like it is supposed to be under the seat and try it out. It came without a boot but I soon found another boot off of one of my friend's mopeds. So I strip down the wires on both ends and tie them together. I pop in the spark plug and rest it against the block and to no avail it makes no spark but when I just use the bare wire (no spark plugs just coil to wire) you can see sparks from the wire to the block.

Here's the interesting part, it produces a good amount of electricity (250v + ac) (keep in mind I’m using brand new spark plugs). So I’m stuck here. I have NO idea why it’s not making a spark out of the plug but it will with bare wire. I tried to trouble shoot and thought it was the key setup (on headlight, it was in really bad shape... didn’t even have a key for it anymore). I took it apart and realized that it was held together by a piece of tape. I snip off the wires and try to reconnect. (Keep in mind... I’m quite frustrated at this point). So now I don’t know what wires I should combine to make things work again.

Other troubleshooting includes unclipping the black/white wire where the carb is and directly hooking that up to the coil. It makes good power... but no spark out of a spark plug.

The only thing I haven't touched but thought about was the coils in under the flywheel and the contact points under there as well. I did eyeball them and they seem to be in good shape. They do look as if they are a bit rusty/corroded but obviously I’m getting good power from them still. I may clean them off but I don’t think that is quite the problem.

So, thanks for reading. Hopefully someone has some idea about this because I don’t want to waste a perfectly good moped just because of no spark. (Everything else is working fine... FYI (carb, injector, etc))

Thanks,
Jared
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Joined: November 29th, 2001, 6:35 am

June 18th, 2005, 4:23 am #2

the blk/wht is ignition power from the magneto thru the points to the primary side of the ignition coil

for the coil to make high voltage and spark the plug, the points MUST OPEN

you can have all kinfs of voltage from the wire with the points stuck closed, but the coil only makes spark when the points OPEN.

the coil is a transformer, the current & voltage have to 'change state' or there is NO changing magnetic feild, a transformer has to have a changing/collasping feild in order to produce power in the secondary winding

check the points



TheMopedWhiz

Ride Mopeds..SAve Gas..Have Fun
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Jared
Jared

June 18th, 2005, 6:26 pm #3

Alright! I cleaned off the points. Checked for proper distance. (.4-.3) when open. I think I may have found the problem. Only thing is I really have no idea how to fix it. I turn the flywheel until the points open up. I then took my multi-meter and checked for continuity between the two points. It showed that there was a circuit. So some piece of plastic in there has been fouled or something and I dont really know where to check first. I have a feeling the owner before me was toying around with it and left out a very imporant piece to insulated some wires but im unsure. Thanks for all your help!!!!

Jared
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Joined: November 29th, 2001, 6:35 am

June 19th, 2005, 6:02 am #4

have you tried to start the bike NOW ?

one side of the points goes to ground the other side goes to igntion

since one sode of the coil is grounded and one side of the magneto is grounded

you WILL read continuty

you need to try and start the engine



TheMopedWhiz

Ride Mopeds..SAve Gas..Have Fun
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Jared
Jared

June 19th, 2005, 4:59 pm #5

I tried getting a spark against the block and it�s a no go. As it was doing before it was making small sparks with the bare wire. I think the guy on EBay sold me a bad ignition coil because everything else is fine.

I did test the coil for continuity, according to the manual. I have a digital multi-meter so it was hard to decipher if anything was wrong with the readings. The last test (test c) between the ground and the power input on the coil had a significantly lower number than the others.

If the coil isn't it... I don�t think this moped was meant to run after I acquired it.

Thanks allot!
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Jared
Jared

June 20th, 2005, 4:13 am #6

HA!! I dont know how I did it but thanks to the mopedwizard my moped is running. now all i need now is a working taillight and headlight. I search around here to see if i can find some details on that.
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