Roll Your Own CDI

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Are You Going to Roll Your Own CDI?

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Ratchetbirds

Ratchetbirds

Member
Jun 12, 2011
125
1
16
Eastern Wash.
impression said:
That's easy.

Since you don't want to make the "white wire" do 3500 turns of 30 gauge wire instead of 3100 turns of 36 gauge...

the higher gauge wire will let you do more 'turns' and keep the same level of resistance, yet his way you will generate more voltage = stronger spark :)

I can do the math for you, but i'm just about to face-plant my keyboard. G'night all :)
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Heya Impression,

That is more than I could have asked for. Thank you for the info and I will probably follow it to a tee. Unless you wake up in the morning and realize you flubbed a decimal or sumptin <G>. Have a great sleep and dream about the nicer weather comin soon....for riding.
 
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impression

New Member
Feb 26, 2009
244
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Syadney,Australia
Ratchetbirds said:
Heya Impression,

That is more than I could have asked for. Thank you for the info and I will probably follow it to a tee. Unless you wake up in the morning and realize you flubbed a decimal or sumptin <G>. Have a great sleep and dream about the nicer weather comin soon....for riding.
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thankyou. Check out the other thread for magneto/stator stuff and keep this thread for CDI/ignition coil ?

http://motorbicycling.com/f50/roll-your-own-magneto-stator-34126.html
 
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impression

New Member
Feb 26, 2009
244
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Syadney,Australia
well, Here's my 3rd prototype for my CDI.


EDIT: > the battery is only there to give you a size comparison against a standard AA size battery

the nest CDI i make will be half this size and have more features

 

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rohmell

rohmell

Active Member
Jun 2, 2010
1,531
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New York
talbotti said:
so heres the parts for my cdi ImageShack® - Online Photo and Video Hosting
witch caps i should use. the red caps are metallized polyester 1uf 400v caps. and the black ones are 1 uf 450v so will i use the red or black ones. how to connect the caps so that they come 2uf and what side of that red cap is negative and positive.
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Use the red ones, the black ones are electrolytic type and will not handle the pulse currents.

Connect the caps in parallel for 2 uF.

The red caps are not polarized, although the outer foil is usually indicated on the cap with a black stripe, but I don't see it in the pic, so connect them either way.
 
J

jamie7

New Member
Sep 5, 2011
31
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0
ontario
Hey Guys,

I just read through this entire thread a couple of times to soak it all in. One thing that I notice is that the ignition coil on the factory kit CDI is inside it, not externally added. Why can't we do that in our modded CDIs? Couldn't we just use the appropriate sized step up transformer in its place or something along those lines?

Maybe we are going for power/size by using an external winding? The one inside the kit CDI must be pretty small - anyone know the specs on it?


Thanks


Jamie
 
rohmell

rohmell

Active Member
Jun 2, 2010
1,531
6
38
New York
jamie7 said:
Hey Guys,

I just read through this entire thread a couple of times to soak it all in. One thing that I notice is that the ignition coil on the factory kit CDI is inside it, not externally added. Why can't we do that in our modded CDIs? Couldn't we just use the appropriate sized step up transformer in its place or something along those lines?

Maybe we are going for power/size by using an external winding? The one inside the kit CDI must be pretty small - anyone know the specs on it?


Thanks


Jamie
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Absolutely you can have the ignition coil in the same enclosure as the rest of the CDI circuit.

One of the interesting things about making your own CDI is using whatever parts that you may have lying around in its construction.

There are many different types of ignition coils that can be used with this circuit, I think it is part of the fun experimenting with different things to find the one that works best in a particular application.
 
Ratchetbirds

Ratchetbirds

Member
Jun 12, 2011
125
1
16
Eastern Wash.
jamie7 said:
Hey Guys,

I just read through this entire thread a couple of times to soak it all in. One thing that I notice is that the ignition coil on the factory kit CDI is inside it, not externally added. Why can't we do that in our modded CDIs? Couldn't we just use the appropriate sized step up transformer in its place or something along those lines?

Maybe we are going for power/size by using an external winding? The one inside the kit CDI must be pretty small - anyone know the specs on it?


Thanks


Jamie
Click to expand...
Excellent idea! I think I shall try to make an all in one CDI/Coil with my next unit. I never even thought about that. Thank you.
 
J

jamie7

New Member
Sep 5, 2011
31
0
0
ontario
Hey,

well that would be nice if we could duplicate the size of the HT engine ignition coil requirements in our ryo cdi. I looked up a standard car ignition coil info. looks like the primary is 100-150 turns of heavy gauge wire but the secondary inside windings are 15000-30000 fine gauge wire. I would assume that the HT/ china girls don't need that much power. I've got a few tv and dvd player power supply - I wonder if the transformers from those may work. Or would they be step-downs? Probably need a transformer from an old power inverter or something.

Anyone got any ideas on the voltage or amp requirements to turn over the HT?


Jamie
 
Ratchetbirds

Ratchetbirds

Member
Jun 12, 2011
125
1
16
Eastern Wash.
jamie7 said:
Hey,

well that would be nice if we could duplicate the size of the HT engine ignition coil requirements in our ryo cdi. I looked up a standard car ignition coil info. looks like the primary is 100-150 turns of heavy gauge wire but the secondary inside windings are 15000-30000 fine gauge wire. I would assume that the HT/ china girls don't need that much power. I've got a few tv and dvd player power supply - I wonder if the transformers from those may work. Or would they be step-downs? Probably need a transformer from an old power inverter or something.

Anyone got any ideas on the voltage or amp requirements to turn over the HT?


Jamie
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Wish I had the numbers for you, but I decided to use a pit bike coil from e-bay. It cost me under $10 and has the plug wire and plug socket. Small in size as well. I posted some pics earlier in this thread of a factory cdi/coil unit I took apart. The coil was ultra small with small windings. I wasn't able to unwind and count but it is deffinately too small in my opinion.
 
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impression

New Member
Feb 26, 2009
244
0
0
Syadney,Australia
Ratchetbirds said:
Wish I had the numbers for you, but I decided to use a pit bike coil from e-bay. It cost me under $10 and has the plug wire and plug socket. Small in size as well. I posted some pics earlier in this thread of a factory cdi/coil unit I took apart. The coil was ultra small with small windings. I wasn't able to unwind and count but it is deffinately too small in my opinion.
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the stock cdi/coil windings are either of the following

1. not enough windings to create a good strong high voltage spark without pedalling hard

2. the windings to fit enough in such a small space are of such a fine wire gauge that there is a LOT of resistance in the wire for the voltage generated which inhibits spark generation...


either way you're better off without it.

I'm using an ignition coil from a mercedes S class car and let me say DAMN it's so nice to start and gives me a really good spark :D
 
J

jamie7

New Member
Sep 5, 2011
31
0
0
ontario
Hey,

I remember seeing that pic you posted (thanks) of the original internals. The coil looked a little mashed up but I did see that it was pretty tiny.

$10 for what you got on e-bay - just can't go wrong. The the plug wire and all.

Some background - I'm a chronic DIYer with just about everything. I've got 2 mb 2stroke kits on the go as well as a 4 stroke non kit in development and a pocket bike engine aching to be installed on something. All of my CDIs are currently functioning just fine - but I want to know that I can do it and have one ready replacement. I've got a couple of bins of salvaged electronic parts for other DIY projects so I'm looking forward to seeing what can be cobbled together.

Also, I just remembered that in one of my electronics parts bins I've got a camera flash that has some big caps and I think a transformer in it - that circuit may be almost exactly made to become a CDI - if it is I'll post it.

thanks for all your input in this thread!
 
J

jamie7

New Member
Sep 5, 2011
31
0
0
ontario
Sorry Impression, I think we posted at the same time and I just saw your post. That's a good point about the substandard nature of the coils in the factory CDI. Also the coils in an auto ignition coil are immersed in oil to control temp. The factory CDI isn't protected as well from overheating.

I don't have a frame of reference for the stand alone ignition coil experience so I should give it a try - sounds nice.
 
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impression

New Member
Feb 26, 2009
244
0
0
Syadney,Australia
jamie7 said:
Sorry Impression, I think we posted at the same time and I just saw your post. That's a good point about the substandard nature of the coils in the factory CDI. Also the coils in an auto ignition coil are immersed in oil to control temp. The factory CDI isn't protected as well from overheating.

I don't have a frame of reference for the stand alone ignition coil experience so I should give it a try - sounds nice.
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bikeignition2.wmv - YouTube

you can see my coil here in this video :)

I must note that i never use "half spark" for easy starts as the bike is crazy easy to start even on full strength spark :)
 
J

jamie7

New Member
Sep 5, 2011
31
0
0
ontario
I was trying to find one of your videos that let me hear the engine running with the ryo cdi. The video named "throaty" is all I could find - is that a good example?
 
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