Roll Your Own CDI

GoldenMotor.com

Are You Going to Roll Your Own CDI?


  • Total voters
    123

rohmell

Active Member
Jun 2, 2010
1,531
6
38
New York
Found schematics on the Russian motorized bicycle forum:
Ãëàâíàÿ
for the CDI, so I'm going to start experimenting, looks very simple and can be tailored for use with any old ignition coil you have lying around.

CDI 1.jpg
CDI 2.jpg
 

Skarrd

Member
Oct 13, 2010
501
2
18
34
Chandler, AZ
do you know if this one will perform ignition retard? or does this one just keep advancing like our stock ones do?
 

corgi1

New Member
Aug 13, 2009
2,272
3
0
KCMO
Oh my did you just call him a retard,this is too much ,I have to get some sleep,lol
 

DaveC

Member
Jul 14, 2010
969
1
18
Boise, ID
The CDI that banned member jaguar makes automatically retards at upper RPMs. There are two jumpers to pull to further tune the CDI if desired.

I can give you a link if you PM me.

I use it and I can tell you first hand it works to lessen vibration in the upper RPM band. My motor has never run smoother, especially for a 66cc. The Puch cylinder head has stiff compression, about 9:1 compaired to the stock 6:1 compression ratio and the CDI fires under those conditions very well. Plug is not quite right with a B8HS but I got my NGK BR9HIX Irridum sparkplug today, right from NGK :)

Now I gotta plug the hole at a mounting stud weld on my tank :p Re-adjust the clutch and back to ridingbrnot
 

Skarrd

Member
Oct 13, 2010
501
2
18
34
Chandler, AZ
The CDI that banned member jaguar makes automatically retards at upper RPMs. There are two jumpers to pull to further tune the CDI if desired.

I can give you a link if you PM me.

I use it and I can tell you first hand it works to lessen vibration in the upper RPM band. My motor has never run smoother, especially for a 66cc. The Puch cylinder head has stiff compression, about 9:1 compaired to the stock 6:1 compression ratio and the CDI fires under those conditions very well. Plug is not quite right with a B8HS but I got my NGK BR9HIX Irridum sparkplug today, right from NGK :)

Now I gotta plug the hole at a mounting stud weld on my tank :p Re-adjust the clutch and back to ridingbrnot
still trying to figure out what he actually changed on the cdi. i got the schematic for the standard kdx200.


also why'd he get banned?
 

DaveC

Member
Jul 14, 2010
969
1
18
Boise, ID
..getting into confrontations with the mods. To the point of them pulling his posts.

I disagree with many things that go on in forums but I like to help people so I usually bite my tounge. I have fired what I call broadsides at people when I think there's an injustice. Gotten threads locked but never banned until I was on the other MB forum and got banned for not doing a search for someone else :/

I can find him if I have to and I do, I want another ignition box for the racer I'm building brnot
 

Skarrd

Member
Oct 13, 2010
501
2
18
34
Chandler, AZ
Some more information about his CDI:
Repairing the KDX CDI
yeah that's were i found the schematic.

honestly i can't see that he really changed all that much. since the base timing is going to be set by the magnets position, perhaps just changing out the capacitor for the 5.0uf size so it tapers off at high rpm rather than just going down farther.
 

Stormsorter

Member
Jun 10, 2010
122
1
16
Jasper County Illinois
I did some digging on his site and found this.
I made my own CDI unit by copying the design of the KDX200 CDI and changing two capacitors.
Maybe DaveC would be kind enough to open his up and tell us the markings on the capacitors. My cdi just burnt out and I can't wait 2 weeks so its build one or buy a stock one and I'd rather build the better one.:-||
 

DaveC

Member
Jul 14, 2010
969
1
18
Boise, ID
The 4.7 uF was changed to 5.7uF, and the 1.5 uF was changed to a metallized polypropylene type.
Thank you for doing that, I consider jaguar a friend and I was reluctant to do that. He put a lot of time into thought and development. I completely understand the "do-it-yourself" nature of motorbikeing. The circuit is so simple I could do knockoff's of his knockoff ;) but I'm not going there....well...maybe after he starts to market them through others :)
 

Stormsorter

Member
Jun 10, 2010
122
1
16
Jasper County Illinois
Would be nice if he had a deal with a store here in the states. If he did I would just order one. If so would just get a stock one for now and order his when I had the extra cash.

Can I assume you meant 5.6uf cant find a 5.7? As for tolerance 10% that's capacitive tolerance and 5% would be ok if not better correct?

Well after further testing looks like both my cdi and magneto died. Must of burnt up the mag trying to start it before I realized the cdi was dead. So it looks like I'm just getting stock for now. Looks like a proper cdi will have to wait a month or two. Might just go ahead and buy it then but he should at least put it on ebay I'm just not comfortable with paypal alone.