Hi all

This thread might be of interest to those that want a super cheap CDI unit for their older XT’s, as a spare/backup unit or to confirm if the CDI is the problem on a non-starting bike.

I have a soft spot for the XT550 since I had one years ago. So I bought a ’83 that I want to restore. The bike had been standing for 10 years.

The first job on the list was to check out the engine. The bike started poorly at first, and then not at all. No spark.

After doing all the measurements, I still was not 100% convinced it was the CDI box. I have worked on burned stators that measured within specs.

So I decided to build myself a cheap/simple CDI to be absolutely sure before buying a new one. New CDI’s are not cheap. Besides, I like messing with stuff..

A guy has done a lot of research and development regarding the CDI’s on the older XT’s, and he has generously put his findings on the web. Really nice of him!!!
Fabriquez votre CDI pour XT600

So I decided to build the simple analog CDI. To be honest I wasn’t sure it would work…

I have not messed with PCB (printed circuit boards) since in school many years ago. But no problem, the cost is low, so no big deal if the thing would not work.

The build:

Board blueprints


The board in solvent!!






Board and components…




Board, long legs on the components, as I planned to re-solder the board.…




Board again…




Notice the professional wiring…






So – I took out the plug to see if I would get some sparks. Kicked the bike… BLUE nice sparks…. YYYeeeess… So the original CDI was the problem, no doubt.

Screwed the plug back in, didn’t really expect the bike to start…. But it did…. And idled just fine. Gave it some gas…. Reved up fine…. And returned to idle and sat there purring.. Wow. Didn’t expect that.

Maybe I can test-ride the bike next week. It will be an interesting ride, the spokes are loose and the swingarm has play, the bike will be wobbling all over the place. Still I am kind of excided to test it, I’ll never grow up I guess…

I’m sure the engine will run kind of silly with this DIY CDI, with the timing advance of 12 deg jumping to 36 deg in one step. But I will keep the CDI as a spare part, since it works. Just need a waterproof box to house it in…


Now for the big question… to buy a decent CDI or build my own programmable one …. Hmmmm…

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Yamaha XT600E '01, Honda XR400 '03, Yamaha XT550 '83

:O nice!

I've been searching for a programmable unit for my 1990 XT600E myself so I can tune it accordingly to the mods...

How would you exactly program that DIY board?


Vando

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http://www.bikepics.com/members/b4nz4i/

Vando, this board is not programmable. The programmable CDI’s are more complicated. The guy that designed this circuit has also done some R&D on a few programmable CDI’s and was kind enough to put it on the web:
Fabriquez votre CDI pour XT600

And, like cyberzar said, TCI is not CDI.

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Yamaha XT600E '01, Honda XR400 '03, Yamaha XT550 '83

And TCI stands for .....??

TCI = Transistorised Coil Ignition & CDI = Capacitor Discharged Ignition

tci is simlar to the old points system where the coil builds charge then triggers the negative side of the coil when the points open except it uses the transistor which gets its info via a pick up.

cdi makes the spark by discharging a capacitor loaded with high voltage (200 - 450 volt) into the ignition coil by using a SCR (Thyristor) on the positive side of the coil.

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XT 630 SUPERMOTO

GSXR750L KMX200

RF900 & GSX400X Impulse Projects
3.9 V8 Rangerover

Thanks for that Wolf, useful info. I imagine a slight drawback with the TCI is that it needs a functioning battery in place. But with no kickstart, it's needed anyway!

Geoff

Thats a sweet job you did there well done

Way too clever for me.......... Well done indeed!!!!

hi there, hey thats a great cdi unit,
just wanted to know if you could give me a discription of the parts you used to make the unit.
and also a real size photo or print of the circuit board.
as i have an 82 yamaha xt400 and all i need to get it going is a cdi unit as it did not have one when i got it.

thanks, greatly appreciated if possible.
ange.

Hi Ange

It's all on this guys website (see the first post in this thread), he is the guy that did all the R&D:

CDI XT600 - Analog

Please keep in mind that this CDI unit has a fixed timing advance. It does not advance the ignition "seamlessly". So you have 12° until a certain RPM (threshold adjustable on the cdi unit) and then 36°.

So the powerband is not ideal. There is a "hit" in the powerband when the 36° advance kicks in. Personally I will get a "hyperpack" or repair the standard yamaha box before I finish the rebuild of the XT550.

To me this is a great/cheap CDI unit to confirm if the default unit is indeed shot, or as a backup unit. Nothing more.

I found a fine screw-top box to house it in...

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Yamaha XT600E '01, Honda XR400 '03, Yamaha XT550 '83

I've got a spare original Yamaha CDI for an XT-550 if you want it, say 100 Euros plus post.

Hey thanks for the all the stuff for the CDI unit, i made one from your link and it works, could not believe it when i saw a blue spark and then it kicked over after 4 cranks. once again i say thanks, this bike i actually found it without a cdi unit in it and most of the lighting and wiring. some guy just threw it out on the street and didn't want it anymore. so i took a chance and now have one myself. thanks again.

Ange, that is great. Free is good :-) Do you have pics of this bike?

Do you have any pics of the CDI build or the finished product? I am interested in seeing how you did yours…

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Yamaha XT600E '01, Honda XR400 '03, Yamaha XT550 '83

hey there G600, thanks for that. give me about a week and i will post up some pics of the bike and of the CDI that i made. i got spray can happy and sprayed the whole bike black. so when you see it its all black and im waiting on the seat and the tank to get fixed. but apart from that it runs very well.

by the way, how do you upload photos on this site??