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Kokusan Denki Transistor Controlled Ignition unit circuit diagram

Bike-Nut

Dec 10, 2017
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Hi All,

Does any know where I can find a Kokusan Denki TCI circuit diagram for a 1996 Kawasai ZR750-D1 motorcycle?

The TCI unit only fires one of the two coils and the units are no longer available from Kawasaki (for some time it seems) so no dealers have a new item in stock.

Kokusan Denki were bought out last year by Mahle and I have spent two months trying to find some info to repair my faulty TCI. I have bought two second hand units for my bike (both reported to be working), however neither works at all! Kawasaki have no information in the UK that they can find and their manual helpfully suggests replacing the TCI. D'oh.

Thanks in advance for any help you can give!

Best regards,

David
 

Bluejets

Oct 5, 2014
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Yours does not work, neither do 2 reportedly "good" units also do not work. Perhaps you have been doing something wrong or do not know what you are doing.
 

Bike-Nut

Dec 10, 2017
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Bluejets: funnilly enough I can't do anything wrong as its a simple black box swap so the replacement TCI either works or it doesn't. I my case neither work and I have swapped them around several times to prove this.

My original TCI fires one coil (two out of four cylinders) but not the other coil and swapping coils around makes no difference; ths coil connected to the black wire output from the TCI fires; the coil connected to the green wire doesn't, therefore the green output has a fault (simple logic). Both coils have +12V on the other end from the ignition switch and both the black and green wires have connectivity from the TCI Connector blocks to the coils. The problem is, therefore, the TCI.

Just need a circuit diagram and then I can repair which is why I came here in desperation.

Fuzz1logic: thanks for that very useful link!
 

Bluejets

Oct 5, 2014
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So how about any connections, wiring continuity, kill switches, pick- up coils/ sensors and associated wiring/connections, fuse links, supply failures under load conditions? Not " fuzzy" but rather "basic" logic this end.
 

Bike-Nut

Dec 10, 2017
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All covered in my posts with the exception of supply failures under load conditions and the pickup coil. The new high capacity battery is providing 13V even when the engine is being cranked so its not a supply failure. The pickup coil was 100 Ohms higher than the tollerance in the workshop manual so changed that and, yes, it made no difference, still only getting the coil on the black wire firing with one TCI; no firing at all on the other two units.

However back to logic: if the TCI unit is unplugged, then another one plugged in and the fault changes, then the fault (whatever it is), is in the TCI.

The TCI is the problem; just need the diagram...
 

Bluejets

Oct 5, 2014
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Can't help with a diagram but I have repaired a ZZR750 ignition module. It luckily was a pre-encased unit where the main supply had been reversed and blew out the main switching transistors. The point being that this particular unit design was pretty bullet proof in that respect, so maybe you could check the same in your unit.
 

Bike-Nut

Dec 10, 2017
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Thanks Bluejets, I suspect that this is the case, although with a keyed connector and the fact that the bike was running (although difficult to start at times) until I stripped it down last winter to repaint parts of the frame, I don't know how the TCI can have been damaged. Of course, this unit is very old (late 80's design) so hopefully will be discrete and some kind of Darlington output stage so may be an easy repair. I have been resisting the urge to take the unit apart incase I damage it to a point where it can't be repaired (not sure how the box comes apart!) and then I will be up pooh creek without a paddle.

I may have to investigate one of the commercial repairers to get the unit sorted; at least they will be able to test under load conditions and simulate the engine running at speed.
 
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