Ignition Coil Question

[D-cat]

Nov 18, 2010 13:22:24 GMT -5 markek said:

So there's no voltage to coil from this kill switch wire. I'm still a little confused with this kill switch. When the engine is running does it provide voltage to kill switch and then when you turn key to off it kills (or grounds) the wire so that engine stops??

Not positive if it has points but I do know it doesn't have a cdi box that other scooters or mini bikes have. On those it seems that the kill switch among other things go right to cdi box.

I guess the next step would be to replace the coil, problem is I'd like to be more positive if thats the real problem. Maybe the kill switch is somehow stopping it from getting spark?? Not sure exactly how I would bypass the kill switch because i don't even know if I have it connected correctly.

You have the kill concept correct, on both accounts. To "bypass" the kill wire, just have it disconnected and hanging in mid air. Make sure you don't touch it while testing for spark; it could push hundreds of volts (and that's just the primary side, the secondary (spark plug) side can push anywhere from 10,000 to 50,000 volts).

I still think you are simply missing the critical component that will bounce back enough energy into the coil to spark it; I don't think it's the coil itself. I see some of the oldest and crapiest lawn mower engines and the coils almost never go bad (unless you're talking an antique magnamatic ignition, but that's different). You are correct about the kill being part of a modern scooter CDI, but there are alternative setups (like yours). It may not have come to you with a CDI box, but I believe it did come to you missing a critical ignition component, whether that be a CDI or electronic ignition kit or even a working condenser, I don't know, but you need one of those three or the coil will not fire.

[markek]

D,

This seems to be the closest wiring diagram to what I have. This drawing does not have a "cdi". I do have the regulator and the starter solenoid.

Attachments:

[D-cat]

That's only a battery circuit diagram, it doesn't address the stator. A CDI wouldn't be in a battery circuit diagram, it has its own isolated circuit; except for a few less common designs, it does not get its power from the battery. I could go into detail on scooter CDI design and function, but it doesn't apply here because you have a classic magneto which changes the design. Even if you had a CDI, it wouldn't be a typical scooter type. What you need to look for, if it exists, is an ignition diagram for that engine. Do you know the make and model of the engine?

[markek]

Chinese something or other. Do you know where I should look on the engine for any make or model?

[D-cat]

It could be stamped on the block or on a plate, and it could be anywhere on the engine.

Tell me, is there only one magnet on the flywheel? and, how are your kludge skills?

[markek]

D,

Here is the coil I have (2 prong version). Does this indicate 1 magnet??

What in the world are kludge skills (I'm almost afraid to ask) ;D

[D-cat]

Unfortunately it would have nothing to do with the coil itself, you just have to turn the motor by hand and count the magnets.

If there was only 1, I was considering the possibility of converting the engine to use a modern DC CDI system, but you'd have to run the wiring and fashion a pickup bracket by yourself, which is why I was asking about your kludge skills (like, how good are you at figuring out and rigging a workable solution that is not manufacturer design?).

It would require:
A DC cdi with connector (maybe get off a junked bike?)
wire, taps, and connectors
scooter type ignition coil
scooter type pickup coil
A bracket for the pickup coil

You'd have to get rid of your current coil, and locate the pickup in its place, preferably on a sliding bracket so you can adjust the base timing, then wire the pickup, a +12v wire (ignition "on" side), a ground wire, and a wire to the new coil into the new CDI. If it isn't already, the regulator output should feed to the battery side of the ignition switch (or you may have trouble shutting the motor off). Don't forget the ground on the new coil too. With this kind of retrofitting, you should have a guaranteed spark, but it will only time right if you have only one magnet on the flywheel.

[tvnacman]

Wow I rember commenting on this post , (D-cat your the man) this is beond me without it infront of me. Mark it looks like your in great hands ( I would not have been able to help you in this one) , Iam reading and watching I see there is plenty for me to learn on this one.

Mark do you have any cut wires or any unused plugs ?

Good luck
John

[markek]

Nov 25, 2010 10:20:51 GMT -5 D-cat said:

Unfortunately it would have nothing to do with the coil itself, you just have to turn the motor by hand and count the magnets.

If there was only 1, I was considering the possibility of converting the engine to use a modern DC CDI system, but you'd have to run the wiring and fashion a pickup bracket by yourself, which is why I was asking about your kludge skills (like, how good are you at figuring out and rigging a workable solution that is not manufacturer design?).

It would require:
A DC cdi with connector (maybe get off a junked bike?)
wire, taps, and connectors
scooter type ignition coil
scooter type pickup coil
A bracket for the pickup coil

You'd have to get rid of your current coil, and locate the pickup in its place, preferably on a sliding bracket so you can adjust the base timing, then wire the pickup, a +12v wire (ignition "on" side), a ground wire, and a wire to the new coil into the new CDI. If it isn't already, the regulator output should feed to the battery side of the ignition switch (or you may have trouble shutting the motor off). Don't forget the ground on the new coil too. With this kind of retrofitting, you should have a guaranteed spark, but it will only time right if you have only one magnet on the flywheel.

D,

I'm guessing my kludge skills are about average, but that said, I'm thinking either i have (1) a bad ignition coil (2) incorrect kill switch connection, or (3) a bad engine.

So I think instead of me trying to reconfigure the setup I have that either I try a new coil or just try and find a reasonable replacement engine. I almost had an ebay purchase on an engine the other day but got outbid by a stinkin dollar. For some reason decent used 49cc engines are hard to come by.

[markek]

Nov 25, 2010 11:11:27 GMT -5 tvnacman said:

Wow I rember commenting on this post , (D-cat your the man) this is beond me without it infront of me. Mark it looks like your in great hands ( I would not have been able to help you in this one) , Iam reading and watching I see there is plenty for me to learn on this one.

Mark do you have any cut wires or any unused plugs ?

Good luck
John

John,

All the plugs were original (at least i think). Some I rewired but didn't really change anything. The only thing that didn't have a plug was the 5 wires that went to the missing keyswitch. I think I have the five wires identified because I have the gauges, blinkers, horn, headlight, etc. working.

Not sure if I have the wire from the ignition coil or the kill switch wire done correctly.

Mark

[Scootless Wonder]

You seem to be stuck on this whole wire from the ignition keyswitch to the coil. This CANNOT be. The coil only sees voltage for periods of time to that it only sparks once every cycle. If a constant voltage were placed at the coil, you would get a continuous spark thus defeating the engines natural combustion cycle.

Now without being there to look at it and going by the pics alone, I can't see the CDI. You have the typical voltage regulator (grey metal component at the top of the first pic) of a 49cc scooter both 2 stroke and 4 stroke. So now you need to look for a little black box (similar in size to the voltage regulator but most likely black plastic). There should be 5 wires coming from it. 2 wires will likely be in a connector the other 3 will have bullet connectors on them. You need to check the black/white stripe wire from the coil using the continuity function of the multimeter to the other end (which should be on the CDI). Check then for AC voltage coming from the CDI on that black/white stripe lead.

[Scootless Wonder]

If you can find that little black box (I'm assuming you have the same simple CDI that I have. It's a 5 wire one wire going to the cutout switch, another to the coil, another to the ground, one to the stator, and I'm assuming the last would be positive voltage).

[markek]

Nov 25, 2010 20:50:56 GMT -5 Scootless Wonder said:

You seem to be stuck on this whole wire from the ignition keyswitch to the coil. This CANNOT be. The coil only sees voltage for periods of time to that it only sparks once every cycle. If a constant voltage were placed at the coil, you would get a continuous spark thus defeating the engines natural combustion cycle.

Now without being there to look at it and going by the pics alone, I can't see the CDI. You have the typical voltage regulator (grey metal component at the top of the first pic) of a 49cc scooter both 2 stroke and 4 stroke. So now you need to look for a little black box (similar in size to the voltage regulator but most likely black plastic). There should be 5 wires coming from it. 2 wires will likely be in a connector the other 3 will have bullet connectors on them. You need to check the black/white stripe wire from the coil using the continuity function of the multimeter to the other end (which should be on the CDI). Check then for AC voltage coming from the CDI on that black/white stripe lead.

Scootless,

This bike does NOT have a cdi.

I think I've determined that the wire from the keyswitch shouldn't be providing a constant 12v to the ignition coil. I think that someone when this bike is running that the coil provides 12v to the wire TO the keyswitch and then when the key is turned off this grounds the wire and kills the engine. At least thats what I think at this point. Still not 100% sure.

What I do know is I'm not getting any spark!!!

[D-cat]

This is the basic magneto ignition. The magnet on the flywheel (not shown) induces current in the primary coil.


The point and condenser set may be replaced with an electronic timing and feedback module (see previous link). This diagram doesn't address kill wire, but it could be located either between the coil and points (low tension grounding) or the positive (spark) end of the secondary coil (high tension grounding), either one will prevent sufficient current from making a spark.

The circuit inturrupter (point or electronic) is important. The simple act of the magnet passing the coil does not produce enough voltage to even step up for a spark. Instead what needs to happen is a current must already be established in the circuit by the passing of the magnet, then interrupted. An interesting effect of DC current is that it doesn't stop instantaneously, but a wave compresses (think of a stretched slinky when you give it a push) causing a voltage spike in the coil. The condensor on a points system absorbs the shock on the primary end and prevents the spark from prematurely discharging on the points and thus maintains the high potential (say about 200v) necessary to step up for an ignition spark. As the magnetic field in the coil is amplified, the secondary side of the coil can reach many thousands of volts, causing a spark to jump the plug gap, collapsing the field and readying the coil for the next pass.

Without the voltage spike from the circuit interruption and subsequent field collapse, there is no spark. That's why I say you must be missing components. A new coil isn't going to solve your problem if you don't have the circuit interrupter. I don't care what your spec sheet says, there's no way on Earth it's a true CDI ignition as it's designed, but it may have an electronic circuit interruption by design. What you need to do is figure out what your potentials are on the leads coming off your current coil. It's possible one is meant to be grounded and the other go to the interrupter.

Edit: Linked image to source; I didn't realize at the time the host server was using refer auths

[tvnacman]

Mark
D-Cat seems to be on track stick with him
John

[markek]

Nov 26, 2010 10:13:48 GMT -5 D-cat said:

This is the basic magneto ignition. The magnet on the flywheel (not shown) induces current in the primary coil.


The point and condenser set may be replaced with an electronic timing and feedback module (see previous link). This diagram doesn't address kill wire, but it could be located either between the coil and points (low tension grounding) or the positive (spark) end of the secondary coil (high tension grounding), either one will prevent sufficient current from making a spark.

The circuit inturrupter (point or electronic) is important. The simple act of the magnet passing the coil does not produce enough voltage to even step up for a spark. Instead what needs to happen is a current must already be established in the circuit by the passing of the magnet, then interrupted. An interesting effect of DC current is that it doesn't stop instantaneously, but a wave compresses (think of a stretched slinky when you give it a push) causing a voltage spike in the coil. The condensor on a points system absorbs the shock on the primary end and prevents the spark from prematurely discharging on the points and thus maintains the high potential (say about 200v) necessary to step up for an ignition spark. As the magnetic field in the coil is amplified, the secondary side of the coil can reach many thousands of volts, causing a spark to jump the plug gap, collapsing the field and readying the coil for the next pass.

Without the voltage spike from the circuit interruption and subsequent field collapse, there is no spark. That's why I say you must be missing components. A new coil isn't going to solve your problem if you don't have the circuit interrupter. I don't care what your spec sheet says, there's no way on Earth it's a true CDI ignition as it's designed, but it may have an electronic circuit interruption by design. What you need to do is figure out what your potentials are on the leads coming off your current coil. It's possible one is meant to be grounded and the other go to the interrupter.

D,

Who the what the....?? Everything you said sounds reasonable (I honestly don't undersatand most of it) enough.

I'm pretty sure, not positive, but pretty sure that I'm not missing any parts.

What if I disconnected everything from the engine and took it off the bike and then tried to start it with just the pull start. Do you think I would get spark??

[D-cat]

With this design, it is irrelevant whether the motor is attached to the bike or not. Honestly, I think that's more work than it's worth. You should get a spark whether you use the pull rope or electric start. The spark is not going to magically appear because you remove the motor from the frame. Have nothing from the coil hooked into the ignition switch right now. Figure out what the wires off the coil have for ohms against ground, and voltage pulse when cranking. If both give you no reading, try between eachother.

[markek]

Let me know if this is correct. Set meter to ohms and put the black lead to ground (or should I connect to battery neg.) and then the red lead to each one of the wires coming off of the coil??

Then switch to volts and check for readings on both wires??

Thanks,

Mark

[D-cat]

You have that correct. Engine block should be fine for the ground.

[markek]

Okay, took some readings today. Started with the ohms reading and was getting approx. 3.5 ohms off of the coil wire that goes to keyswitch. Was getting approx. the same from the ground wire but was very sporadic and found that I had a bad connection. Thought this might have been my problem all along.

Re-soldered both connections and took more readings. The readings now seem to jump all over the place with the ground wire averaging approx. the same and the keyswitch wire at about 1.6, but again jumping all over.

Tried to turn over again to see if my bad connection was preventing spark but still get nothing.

My coil is kinda weird in that I put a credit card in between for a gap but is very hard to actually set. Too tight and I can't pull the pull start (or electric start) at all. Loosen coil up a little and then I can use pull start. Either way no spark yet.

I will take some readings off of coil tomorrow while cranking engine to see what I get.

[D-cat]

The readings are only meaningful out of circuit, e.g. not connected to the keyswitch or ground. You have a red and a black wire right? Right now, we don't even know which one, if any, is supposed to go to the key switch and at what connection. Were the random readings while the engine was stationary and the magnet was NOT under the coil? I'm sorry I didn't mention that earlier, but that's when to do the ohm reading. Only the volt reading is done while cranking.

Yes, setting the magneto gap can be difficult. I hope you didn't use an active credit card. It has to be set while the magnet IS under the coil, since it sticks out a little bit (usually) and setting it anywhere else may result in the flywheel being unable to turn or premature grounding of the coil core. The closer you can get the magnet to pass the coil without touching the more powerful the spark will be, but if it touches, the field will be stationary (no current induced). This is why having a match book cover or credit card in between works well, but you still have to dislodge it after the bolts are tightened down.

[markek]

Nov 28, 2010 14:16:44 GMT -5 D-cat said:

The readings are only meaningful out of circuit, e.g. not connected to the keyswitch or ground. You have a red and a black wire right? Right now, we don't even know which one, if any, is supposed to go to the key switch and at what connection. Were the random readings while the engine was stationary and the magnet was NOT under the coil? I'm sorry I didn't mention that earlier, but that's when to do the ohm reading. Only the volt reading is done while cranking.

Yes, setting the magneto gap can be difficult. I hope you didn't use an active credit card. It has to be set while the magnet IS under the coil, since it sticks out a little bit (usually) and setting it anywhere else may result in the flywheel being unable to turn or premature grounding of the coil core. The closer you can get the magnet to pass the coil without touching the more powerful the spark will be, but if it touches, the field will be stationary (no current induced). This is why having a match book cover or credit card in between works well, but you still have to dislodge it after the bolts are tightened down.

Alright D-Cat,

I just saw that BOTH wires from the coil go to the keyswitch. I originally thought one went to a wire nut with some other ground wires.

Ohm readings are all over the place, sometimes high sometimes zero. I would guess that the average of the readings are one prong wire is 4.6 ohms and the other prong wire approx. 4.5 ohms. If I meter between the two wires I get 2.7 ohms.

I have to say tho that I was getting all kinds of differerent readings.

When cranking should I set meter to DCV?? I tried a couple different settings on meter and I was getting 0.1 (I think this was with dcv) and me pulling on pull string.

[tvnacman]

this is getting more interesting.
looks like your getting a pulse from the p/u (I think it should be a/c ) see what D-Cat says

[D-cat]

AC is at least more reliable. How are the leads on the meter? If you short them together, are you getting a steady 0 ohms? I want to make the problem is definitely coil related and not with the meter.

[rosscoross]

hi all i came across this thread while trying to find out why my motor wont start i have the same problem no spark and i carnt seem to find any way that the engine can know when to spark the engine number is D1E41QMB chinese i think but no (cdi) fitted and defo no points i dont under stand
the prob is i was given this atv as a non runner but the only info i can find on this engine is in scooters parts
i do hope one of you figure it out
its lost me
ross

[markek]

Nov 29, 2010 0:20:51 GMT -5 D-cat said:

AC is at least more reliable. How are the leads on the meter? If you short them together, are you getting a steady 0 ohms? I want to make the problem is definitely coil related and not with the meter.

When I put meter on ohms and set to 20 and touch leads together I get 0.

Retested coil again and got 0.4 ohms on one wire and 1.4 on the other. Set meter to AC and got 0 and 0.2 on the wires when cranking.

[D-cat]

That's pretty minuscule, how about across the two leads?

[markek]

Nov 19, 2010 1:02:04 GMT -5 D-cat said:

Nov 18, 2010 13:22:24 GMT -5 markek said:

So there's no voltage to coil from this kill switch wire. I'm still a little confused with this kill switch. When the engine is running does it provide voltage to kill switch and then when you turn key to off it kills (or grounds) the wire so that engine stops??

Not positive if it has points but I do know it doesn't have a cdi box that other scooters or mini bikes have. On those it seems that the kill switch among other things go right to cdi box.

I guess the next step would be to replace the coil, problem is I'd like to be more positive if thats the real problem. Maybe the kill switch is somehow stopping it from getting spark?? Not sure exactly how I would bypass the kill switch because i don't even know if I have it connected correctly.

You have the kill concept correct, on both accounts. To "bypass" the kill wire, just have it disconnected and hanging in mid air. Make sure you don't touch it while testing for spark; it could push hundreds of volts (and that's just the primary side, the secondary (spark plug) side can push anywhere from 10,000 to 50,000 volts).

I still think you are simply missing the critical component that will bounce back enough energy into the coil to spark it; I don't think it's the coil itself. I see some of the oldest and crapiest lawn mower engines and the coils almost never go bad (unless you're talking an antique magnamatic ignition, but that's different). You are correct about the kill being part of a modern scooter CDI, but there are alternative setups (like yours). It may not have come to you with a CDI box, but I believe it did come to you missing a critical ignition component, whether that be a CDI or electronic ignition kit or even a working condenser, I don't know, but you need one of those three or the coil will not fire.

So I finally broke down and bought a new ignition coil. Gapped it, made a slight pull on the pull starter and lo and behold SPARK!

Haven't tried to actually start it yet, but I must say this was a big hurdle for me. I didn't think I was actually missing any parts, just wasn't sure what part was bad. $25 dollars later and wallah, nice blue spark.

[markek]

Well, now that I finally have spark I had some time to see if it would actually start. A little starting fluid in carb, a couple pulls and she fired right up. Pleasantly surprised.

A little difficult to pull the pull start. Didn't want to brake it so I didn't go too crazy with pulling.

Couldn't get the electric start to work correctly. Would turn every once in a while but not enough to start bike. Battery is good. Connection to the little part coming out of engine near pull start needs to be redone. Anyone now more about this!!!

Need a new throttle cable and I think I'm ready to go.