Roll Your Own CDI

[ducedave]

Well it runs but you have to rework them I start off with about 30* to much advance at idle so reworked the magnet and that helped as it stands-replaced 82onm. +-5% = 81ohm. with 94ohm. and the advance at fast idle came down still in advance and content though out rev , at near stall idle timing back off a hair < 3* replaced 560ohm. +-5%= 546ohm. with an extra 47ohm= 593ohm. and will see if that helps in the morning I think the advance is way early and running into the retard or the retard is early flattening the advance. the 2.2uF.small cap maybe replaced with a 3.3uF. if the 593ohm. opens the advance curve, we'll see what works I never give up!

 

[ducedave]

I use a timing light hooked to a car battery HTs have no timing marks so I'm not setting the timing just see what the advance and retard look like or if there is any there's no tachometer so it's best guess and ride test- right now I'm looking for a low idle and a good upward curve to make tork through low to higher mid revs. I'll have to resist the power increases from the magneto to tailor the advance curve but this throws the power to the retard side too early so more resistance and a bigger cap I hope will do it

 

[Kristof]

Ok, so I built a cdi...I think.

I had a coworker help me out, so he ordered the parts from Digikey and put it together.

Let me know what you think. Any concerns, please let me know. Keep in mind, i have no training in circuitry, but i have some knowledge of electricity.

 

[ducedave]

OK-I'm going back to the starting point the problem isn't resistance it's FREQUENCY!!!!
yes as the V. ^ a cap will charge quicker and dis charge sooner giving a curve but the simple cdi fires at it's set time with no regard to the retard so I'm now going to put a cap in the simple cdi for two reasons (1) to give a curve (2) to coughs a low frequency filter as the cap is to be placed AFTER the 82ohm. resistor my hope is that the low will go through the simple cdi and give a curve as the RPM=FREQUENCY ^ in tell the RPM=FREQUENCY are blocked and the retard at it's ^ RPM=FREQUENCY as it's is ^ as it's resistor is after the cap

So I will see if this is the trick I'll let you know.

 

[Kristof]

So, did i get it right? Did I use the right parts?

 

[ducedave]

So, did i get it right? Did I use the right parts?

hay- that cap is to low of a volt-you need 800volts or better- used two 1uF.650v. like this = not this -- so that's 2uF. 1,3000 V. and it fires the coil-I couldn't tell if it was wired right it looked like it was just solder-I used 0.5 watt resistors on the basic cdi

 

[Kristof]

hay- that cap is to low of a volt-you need 800volts or better- used two 1uF.650v. like this = not this -- so that's 2uF. 1,3000 V. and it fires the coil-I couldn't tell if it was wired right it looked like it was just solder-I used 0.5 watt resistors on the basic cdi

That cap is rated 630v DC.

Will the 2 watt resistors not work with this?

 

[ducedave]

That cap is rated 630v DC.
Seems low but it's in there so give it a try, what do you have to loss? I hope it work-
Will the 2 watt resistors not work with this?
the 2 watt cost more $ then the 0.5 watt-I'm off to do Battle with my cdi trying to get it to advance and retard I'll
see you latter

 

[Kristof]

K, so I took it out for testing. It was very rough.

I set it up using only electrical tape, so maybe the vibration is causing missed spark. But it also seems delayed. Maybe carb tuning?

I need help.

 

[ducedave]

K, so I took it out for testing. It was very rough.

I set it up using only electrical tape, so maybe the vibration is causing missed spark. But it also seems delayed. Maybe carb tuning?

I need help.

so it ran vary good!!!-mine is so retard I had to file the magnets key way to get some advance

 

[decoherence]

so it ran vary good!!!-mine is so retard I had to file the magnets key way to get some advance

awe! it can't help that it is a retard.
lol.

 

[Kristof]

Ok, so I fixed the connectivity issues, but at idle it is rough and it takes longer to accelerate. I could potentially flood the engine, it does not react as well as the stock cdi. Maybe I did something wrong?

Where is rohmell? He probably can figure this out.

 

[ducedave]

Ok, so I fixed the connectivity issues, but at idle it is rough and it takes longer to accelerate. I could potentially flood the engine, it does not react as well as the stock cdi. Maybe I did something wrong?

Where is rohmell? He probably can figure this out.

the cdi is it the basic or the retarding the basic is no advance on retard -and the advance and retard is a tough not to crack

 

[Kristof]

the cdi is it the basic or the retarding the basic is no advance on retard -and the advance and retard is a tough not to crack

So would that explain in the loss of power and top speed?

 

[Kristof]

Answer:

Ok, so I think this is what i need to solve my problem.

1.) How is this different than the Jaguar CDI?

2.) Is the Jaguar CDI better, if so...how do i build that with the parts that i have already?

3.) What voltage is that 2.2uf cap rated at?

4.)Rohmell, Will your $50 cdi be better than the $75 jaguar cdi?

 

[impression]

well i got a couple of Ignition coils from a couple German Cars at the "junkyard"
the orange top one is from a mercedes E class 380 that was in pristine condition and was wondereing why it was even there at the place.. The other black one was from an unknown 80's car but it's also Bosche like the first however It was made in Australia rather than Germany.

But hey for electronics the ones i like to avoid are

-Made in japan ( pre 95)
Made in China ( in general )

the spark plug cable that came with the red top coil has West Germany stamped on it... :O

 

[impression]

hmm i think the wire is glass/carbon and not copper /cries....

note the white fibres coming out ?

 

[ducedave]

So would that explain in the loss of power and top speed?

yes that would be it

 

[ducedave]

Ok, so I think this is what i need to solve my problem.

1.) How is this different than the Jaguar CDI?

2.) Is the Jaguar CDI better, if so...how do i build that with the parts that i have already?

3.) What voltage is that 2.2uf cap rated at?

4.)Rohmell, Will your $50 cdi be better than the $75 jaguar cdi?

5.)are you coming out to Grange to race Oct. 22 Trip distance: 100.1 mi Time: 1 hr 42 mins from Aliso Viejo, CA

6.)I hope to have my cdi running for the race

7.)Grangé Motor Circuit
20455 Central Rd.
Apple Valley, CA 92307

 

[GearNut]

hmm i think the wire is glass/carbon and not copper /cries....

note the white fibres coming out ?

There's nothing wrong with a carbon core wire.
I say run it if it is still good.