[auto]

Helping my son sell my old vision and keep his new one running.Just went through a rash of TCI failures.Has anyone had success diagnosing and repairing a bad TCI unit. Or point us to someone who repair/upgrade these units.

[jefferson]

There really isn't that many cases of tci failure that I know about. Since you are having several I would make sure you have the wiring correct. The plug from the stator will plug into the tci and fry it. The plug from the ignition and stator are the same so I would check that first. You didn't mention if it takes some time for this to happen or what.

[auto]

I think I killed one that way. The one that went bad on my sons bike ,just failed.It had been running fine for some time. Bad design on Yamaha part to allow connector to cross fit.If anyone has one to sell I'm interested.Yes I know there on ebay.

[fret not]

There is a reliable source in the Czech Republic, Ignitech,  They make ignition and fuel control modules for various applications and can supply one for the XZ550.   

http://www.ignitech.cz/english/aindex.htm

[Prophet Of Doom]

I have a graveyard of about a dozen TCI's I've gleaned from parts bikes and parts sales (plus my own bikes).  Failure is more common than you would think, and not all from plugging the wrong wires I'm sure.  Mostly they just stop sparking in one lead, but I've had one that sparked both plugs but wouldn't advance.  It idled fine but produced no power at higher revs.

Near the bottom of the Resources post is Leather's musings about the TCI workings and repair - Give that a read.


+1 for the Ignitech - they are great units much loved by the Germans and available in regular "Sparker" or programmable "TCIP4" model.  The programmable can give you 3D ignition curve if you fit a TPS or MAP sensor, and can be re-used on just about any bike by re-flashing it.


There are also much cheaper TCIs available on aliexpress.com for the XZ550 - can't vouch for these though.

[fret not]

The main problem I found with trying to repair a TCI unit was getting it apart cleanly and without damaging anything.  It requires unsoldering a bar connector from the PC board so the board can be removed from the case.  Then, after replacing any bad item on the PC board it all has to go back cleanly into the case and be resoldered.  All the little parts have numbers on them but you need a really good magnifying glass.  (take a pic with a digital camera, then enlarge it - had to do this to read numbers on some jets)

[auto]

I actually found and repaired the issue.Same condition and location on three TCI units. Break in the circuit board copper band.looks to be heat and age.opened up the back on two of them and transistors and diodes seem to test good.The two zener diodes will test bad untill you remove them.Question I have is there seems to be two types of boxes.One with a label the other with out.The one with a label has a jumper wire on the board and row less of resistors.Any idea which is early or late production? any difference in performance? Have most of you cut the yellow rev limiter wire to the TCI box?

[Walt_M.]

Have you looked at the Dave's electrical FAQ tab in the Technical section,  it's at the top of the page, in the blue. He did a great write up on the TCI, well worth the read.

[ArrrGeee]

I actually found and repaired the issue.Same condition and location on three TCI units. Break in the circuit board copper band.looks to be heat and age.opened up the back on two of them and transistors and diodes seem to test good.The two zener diodes will test bad untill you remove them.Question I have is there seems to be two types of boxes.One with a label the other with out.The one with a label has a jumper wire on the board and row less of resistors.Any idea which is early or late production? any difference in performance? Have most of you cut the yellow rev limiter wire to the TCI box?

auto, that is great news, I spent some time trying to repair one of these, replace a bunch of parts but never got
the rear cylinder sparking again, I eventually replaced it with an ignitech unit.
however, I and probably a few of the other guys would be interested in what you found, maybe some pictures if you can swing it.

thanks!

-Ron


to answer your question, yes on cutting the rev limiter, it's one of the first things the guys do when
the bike has running problems.

[injuhneer]

I agree. Some photos of the repair or the defect/failure would be great.