Tci

[mack]

Been wondering about the TCI on my LH. Does anyone know how it receives the signal and interprets the demand to avance or retard the timing. Mines working fine so don't panic. I am just curious as to how yamaha bridged the mechanical to electronic requirement.

[crazy steve]

I wondered the same thing about the XJ ignition, and after researching the XS/XJ manuals have come to the conclusion that the 'vacuum' advance is a either/or affair; there's simply two curves, and it switches between them. A easy way to check this would be to connect a vacuum pump/gauge to the switch, then see if you get a gradual change in advance at a specific RPM depending on how much vacuum is applied or if it's a case of reaching a 'trigger amount' of vacuum to activate the switch in curves. I suspect the latter....

This is a fairly common way of changing curves on 'simple' electronic ignitions (either/or), the sensor calibration needed and computing power for a gradual curve change wasn't common when these were built...

[mack]

thanx Steve

Thanx Steve, more voodoo. Welcome back, by the way.