Capt Zoom, I have no idea what ignition Triumph uses, but the XS650 never in all the years produced did it ever have a CDI. Points or a TCI is what it has.
Leo
Leo
After much thought I think this is auto advance ignition was a bad idea! I think they would have been further ahead to set it up for a fully advanced ignition with a circuit and a "button" to retard the spark for cold starts.... I'm thinking back to the day when Harleys and Indians and many more...had a mechanical way of retarding the ignition for starting. The only time it was necessary to retard the spark was for the first cold start of the day....or they would kick you back...and to intentionally retard the spark at high rpm and create magnificent backfires that would rock the neighbourhood! I was bad for that one!!!!!!![]()
As noted in my thread about the bad flat spot off of idle, I'm beginning to wonder if this isn't an ignition problem. So I pulled the TCI module and started examining it closeley, the circuit board and solder joints on mine are actually of pretty nice quality (particularly if you consider when it was made).
This module is labeled TID12-018, then 4M4-10, then 007. 4M4 means it is an XS650 part, the 007 I think is the version.
Here's a picture of the component side of the circuit board:![]()
the back or conductor side:
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and the only bad looking component I can find:
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It's visible at the end of the row of diodes and resistors, right next to the gray and black capacitors. One end looks corroded and possibly overheated, the other side of the board looks fine. It looks almost as if it 'popped' and spit something out. It's a Zener diode, the board is marked 'ZD1' underneath it. My diode test function on my multimeter says I have continuity both ways on it which I understand to be a Zener property.
So my questions are: how do I identify this Zener diode to find a replacement and is it likely it could be the source of the 'won't rev up' problem I am having? One end of this diode (the '+' side) goes to the black/white wire which goes to the ignition pickup.
EDIT: FWIW, according to some Googling Zeners are used for 'signal generation'. Maybe...
Woops, meant to include that. It's a 1980 650 Special. About Zener diodes: a 1N4742 is 12V, a 1N4743 is 13V and a 1N4744 is 15V. Radio Shack carries only the 1N4742 but the others are easily sourced online. Zeners are difficult to properly test with a standard multimeter, there should be continuity only one way until the gate voltage is reached at which point it now beomes 2 way.
One end of this one goes to the black/white wire to the pickup coil which is why I think it separates the pickup signals until a certain voltage is reached and the pickup should generate a higher voltage signal as the speed is increased. So this may very well be the 'signal' for the IC that a certain RPM is reached and it's now time for the IC to do something different.