modified cdi and cr 80 coil

[Thud]

I have one of these kits...I need a larger (or more) magnets for the dwell timing, & I need to replace the zeener for a litle higher voltage (& look up the transistor to see if it will work at my LiPo battery total loss system I bought it for)

Mostly I am curious if we could make the timing advance/retard with the cap specs.

I can change & test components but I am ellectarded when it comes to circute design. (i'll hack all day long LOL)

I am totaly open source if we can design our own for a few bucks....I would even etch the boards for a batch if guys wanted to build one.....any one wanna team up?

 

[rohmell]

I have one of these kits...I need a larger (or more) magnets for the dwell timing, & I need to replace the zeener for a litle higher voltage (& look up the transistor to see if it will work at my LiPo battery total loss system I bought it for)

Mostly I am curious if we could make the timing advance/retard with the cap specs.

I can change & test components but I am ellectarded when it comes to circute design. (i'll hack all day long LOL)

I am totaly open source if we can design our own for a few bucks....I would even etch the boards for a batch if guys wanted to build one.....any one wanna team up?

Do you have a schematic for that unit? Maybe can be modified for use with the MB engines.

 

[Ryobusa]

Hi, this is my first post, so hello all, nice forum lots of great info.

I've been following this thread and have been designing a PCB with ExpressPCB, neat program and its free. I've completed the KDX CDI schematic and my first shot at a PCB. But I'm no expert just a hobbyist who acquired a bike with a dead CDI, After seeing some of the schematics offered by rohmell, I'd now like to incorporate a resister pot to be able to fine tune along with a possibly external thermistor to monitor engine temp and adjust timing and have jumpers or switches to activate these extra features.

I have attached my work in a a ZIP file.

 

[rohmell]

Nice work, Ryobusa, and welcome to the forums!

Looking forward to seeing your PCB designs for the KDX CDI and the 'roll-you-own CDI!

 

[skrew37]

This is getting better and better everyday!

 

[rohmell]

On the PCB layout, there are two STR+ designations, also you may want to think about rearranging some of the components and making the COIL+ trace shorter, it might act like an 'antenna' for the SCR pulses and affect the dv/dt triggering.

 

[Ryobusa]

Thanks for the feedback, I fixed the double STR+ typo, and created a new file(CDI-2-Trim pot) keeping in mind your input on having the COIL+ trace as short as short as possible. This one has a potentiometer to trim the spark advance based on Rohmel's supplied diagram. This will just have a straight timing curve as I dont have the high RPM spark retard circuit and its extra caps, I'd love input on adding that and a thermistor to alter timing based on engine temp. I think I will build this simple circuit first and then try and get fancy.

 

[rohmell]

Very nice work, Ryobusa.
I am sure that I speak for many when I say thank you for your efforts.

 

[Scootershack]

if you can figure out a temp guage for the bike i would maybe be interested in buying one from you. good luck on it..your way smarter then me, haha.

 

[DuctTapedGoat]

A temp gauge is simple stuff - I could pull the one I have on my PC off right now and throw it on the bike. You'd just want to bolt to one of the fins in the front of the jug or head.

 

[Ryobusa]

I agree a temp gauge would be pretty simple, Im sure there is something you could buy off the shelf for that application. I want to adjust timing based on temp like the KDX CDI does only have it tailored to our engines and even make it adjustable so you can tune the CDI to match aftermarket parts such as heads pistons and cylinders which may allow more timing advance than a bone stock engine. I just bought a bunch of parts, and instead of the prototype board they seem to use in the $75 CDI kit, I'm going to be etching my final board on a single sided PCB. So my end product should be more rugged and look a bit more professional. I will keep you all updated, also any suggestions for other features would be great, I was thinking of including a half wave rectifier to charge a battery off the white wire, or even having the ignition system powered by a battery, but after reading some threads it seems 3 watts is all you can really get off the white wire's coil so I don't think its worth it. I also wanted to say thanks to all here, I might have some basic electrical knowledge but thanks to forums like these I'm learning more and more, I can draw a CDI schematic from memory now, couldn't say that last week hehe.

 

[Big Boy]

It smoothed out the vibrations for sure . You get to run a real coil that's a plus . And you have four timing curves to choose from . I have done a lot of work to my motor besides the Cdi box , I built a pipe for it cleaned up the ports and changed the head the bike has picked up some mph and runs real good with no four stroking at all . The only thing left is for it to blow up now lol .

How I chose a different timing curve?

 

[Thud]

Do you have a schematic for that unit? Maybe can be modified for use with the MB engines.

I can sketch it up when i get a minute (absolutly burried in work for a few days).

Exciting stuff going on in this thread...

 

[rohmell]

Another pic of the CDI:

 

[buck0]

if you can figure out a temp guage for the bike i would maybe be interested in buying one from you. good luck on it..your way smarter then me, haha.

The temp gauge from Pistonbikes and treatland.tv have enough wire so you can mount it on the handlebars.
Pistonbikes has some temp gauge for sale TTO - Temp Gauge

treatland.tv but their out of stock trail tech digital temperature gauge

I use a traxxis temp gauge for radio control cars Traxxas Part I just wrap the cord around the spark plug. It was running hot one day when I was going up a hill and read 390 degrees. I can only take a reading right after I shut down the engine. If the temp gauge is on, theres alot of interference and cannot take a reading. I dont know what the max temp reading is.

You can also use Venom Venom Racing VTM Micro On-Board Temperature Monitor (Green)

 

[buck0]

How I chose a different timing curve?

You remove the jumpers. There are 2 of them. "A" is for idle and going up hill. "B" is for top end. Right now my setting is "A" jumper is off and "B" is on.

 

[Ryobusa]

I built my CDI, and mounted most components, I'm still unsure on a the resisters. When I first tried the CDI on the bike I got nothing, no spark, so I pulled (D4) and (R1) and set the pot to 18 and 82ohms and she fired up and I got to ride my bike for the first time under gas power, but then it died after only going half way around my block. I fiddled with the pot, tightened my connections and pulled the plug out. I pushed the bike with the clutch dumped and eventually I got spark again. Went for another short ride then again lost spark, and now I can't get it back. I checked I am getting voltage on the blue wire and even the red wire to the coil. I might also try adding one more capacitor I could not get a 2.0uf 250V polypropylene I had to use 4 0.47uf caps in parallel so I only have around 1.8uf as tested on my meter.
I'm using a 6volt coil from a 79 dodge I had laying around.

I have attached my latest .pcb file

Note: The jumper for the caps is the only one installed and again D4 and R1 are pulled

 

[rohmell]

I scoped the pulses at the cap around 318-320 V on mine, so maybe you are breaking down your 250V caps.
I would try to have all components rated at least 400V.

A '79 Dodge would have been a 12 volt system, no? I think 6 volt systems were gone by the '50s.

 

[kusanagy100]

hi, i found this details.

im not sure, but for me te conection of these resistors is

Greetings friends, and that will not freeze the post

 

[DuctTapedGoat]

Heylas Kusanagy100 - those pics are way too small to read, mind reposting some larger ones?