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Old 03-07-2010, 03:51 PM   #58
G600
Gnarly Adventurer
 
Joined: May 2009
Location: Iceland
Oddometer: 425
Thanks guys, for the info regarding the CDI's.

After doing all the measurements, I still was not 100% convinced my problem 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!!!
http://www.transmic.net/en/home.htm

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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