Magneto

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pos

pos

Well-Known Member
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3,685
Location
West Yorkshire
Hello,

I know this is in the wrong place, but I could do with some information from all you familar people. Basically, can someone tell me if this:
Scooter Magneto Two Stroke alone can be attached to my spark plug on my little dirt bike, or do I need some other gubbins to make it work? It's a kick start without any electronic controllers and that.

Cheers
-Pos
 
Only if it'll fit onto your crankshaft spindleand the mounting holes for the gubbins will line up, and if the crancasing will fit back on after you've fitted it. Oh and then you'll need an ht coil to fire the spark plug.
 
it's a little italjet 50CC dirt bike (one of those little things). Basically it's been sat in my Grandads' shed since I was about 5 and I've just decided to try and get it running. Last problem I had was the carb, but I've managed to fix that. Now the ignition coil has melted! Does that unit not have an ignition coil built onto it?

Where and how exactly do they fit to the whole assembly? Like this for example:ElecParts E ::part 5:: Ignition Coil.: Kazuma Falcon 250 Part 92 Baotian Scooters, Kazuma Quads, Dirt Bikes and Spare Parts - PetrolScooter UK.
 
The magneto is like a cars alternator. it just provides power to the battery and a live feed, via a set of points to an HT coil. Like the one in the picture you posted. The coil just mounts up out of the way. Usually under the seat or tank. and as I said a wire runs from a set of points to the coil. Look for a the wires coming out of the bikes engine casing and use a multimeter to see what voltages are coming out of them when you spin the engine over. There should also be a voltage regulator to convert the AC output to 6V DC. which will go to a battery for the lights & horn. Then locate the points and check the timing. Easiest way is a small bulb with small crocodile clips on clip one end to earth and the other to the output wire from the points. Everytime the points open the bulb should light up. then remove the sparkplug and put a screwdriver or pencil in the bore and turn the engine over slowly the points should open slightly before the piston reaches tdc. Which will cause the bulb to glow (you need a charged battery fitted to the bike for this to work). Once you've got it running you can fine tune the timing by ear.
 
Don't get me wrong! I had the engine in bits in less than 10 minutes to check everything looked alright. It's just this electrical side that I don't quite understand, mainly because of the difference between new and old electrical components. Newer magnetos / stator plates don't use points, they just have an electronic regulator.

The old plate that my little bike has, only has two coils, one of which must be the ignition coil because the HT wire comes straight from it to the spark plug cap. That's the bit I don't understand. Similar looking modern day stator plates / magnetos also have two coils (or more) but not an ignition coil? How can my older unit have worked fine with just one "other" coil and one ignition coil built on!?

Just as a note, the bike has no other electronics. The only wiring is the spark plug wire, an earth (supposedly?) and the kill switch. There's no lighting or a horn or anything like that. Also, if I was to test the timing with a bulb, would I not need a much higher voltage bulb than just 12V? I thought the whole point of a magneto was to generate a massive amount of amps?

Thanks again
-Pos
 
pos said:
Don't get me wrong! I had the engine in bits in less than 10 minutes to check everything looked alright. It's just this electrical side that I don't quite understand, mainly because of the difference between new and old electrical components. Newer magnetos / stator plates don't use points, they just have an electronic regulator.

The old plate that my little bike has, only has two coils, one of which must be the ignition coil because the HT wire comes straight from it to the spark plug cap. That's the bit I don't understand. Similar looking modern day stator plates / magnetos also have two coils (or more) but not an ignition coil? How can my older unit have worked fine with just one "other" coil and one ignition coil built on!?

Just as a note, the bike has no other electronics. The only wiring is the spark plug wire, an earth (supposedly?) and the kill switch. There's no lighting or a horn or anything like that. Also, if I was to test the timing with a bulb, would I not need a much higher voltage bulb than just 12V? I thought the whole point of a magneto was to generate a massive amount of amps?

Thanks again
-Pos
Click to expand...

No the HT Coil produces the huge voltages the magneto is just a 6v generator. The lamp goes on the LT wire from the points and is only 6v and hardly any amps at all it doesn't shoot up until it's gone round the windings in the HT Coil. Hence why the wire to a HT coil is just a thin one and the HT lead is a big thick fooker.
 
Actually having thought about it I did used to have a little moped when I was about 14 and the coil was mounted to the side of the engine and was fed directly from the magneto. A bit like a Lawnmower engine. I suppose yours could be similar. But it was 30 years ago. And my memory isn't as good as it used to be.
 
Cheers Red. It is about 15 to 20 years old, possibly a little more. I've got an old lawnmower engine in the shed which I might be able to strip down. I'll have a look. Thanks again

-Pos
 
With one my omy old lawnmower engines i found that the magneto had broken down, but nothing I found would work as well, you would be best looking for a proper replacement.

try bob wright motorcycles, i think he may know somewhere (if you google that itll come with his website)
 
boydy1989 said:
With one my omy old lawnmower engines i found that the magneto had broken down, but nothing I found would work as well, you would be best looking for a proper replacement.

try bob wright motorcycles, i think he may know somewhere (if you google that itll come with his website)
Click to expand...

Cheers Boydy, I'll have a good look on his site and contact him!
-Pos
 
Obviously they are.?? As the magneto is spinning it will have a sensor on it that sends a signal to the coil side of things that breaks the current and causes the coil to excite and create an high tension current which is sent down the HT lead to the spark plug.
 
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