the LT wire on a CDI bike carries a much higher voltage than

the LT wire on a TI bike

If the tacho can handle this then yes, otherwise it may be safer to

use an electric tacho that uses a wire wrapped around an HT lead



Its possible to tap into the pulser wires of course

and as the bike uses a wasted spark system it will

pulse at true rpm.

 

Yes so thats the other thing I wanted to confirm if this bike uses wasted spark or if it shoots the spark on once every other revolution per cylinder.



LT = ??

TI = throttle injected?

HT = ??

 

I believe Reg is using the following abbreviations:



LT = Low tension wire (the small, low voltage wire going to the coil from the CDI.)



TI = Transistorized ignition (The ignition system that all GL's and 1982+ CX models use.)



HT = High tension (The wire that goes to the spark plug from the coil. Considered a high voltage wire as it probably carries about 30,000+ volts)

 

Yes, the bike uses a "wasted spark" system, so the coils spark one per revolution (giving a true RPM value). I see no reason you can not tie into the input line on one coil (thats what I am going to do with the electronic tach Im making), but you may need to condition the signal a bit based on what the tach you use requires (mine requires a pulse, so I can capacitively couple it). Best to stick to what the manufacturer recommends to be safe unless you know electronics and can make sure the signal is made compatable.

 

Does anyone know if the ignitech unit provides a n rpm signal wire for accessories?

 

I have a feeling it does

the main connector has unused pins for TPS, shift lights and stuff

and seem to recall seeing an rpm output.

This is from memory mind you, best check with an owner.

 

I just got finished doing some reading in the FSM. Would it cause a problem for a tach if using the low tension wire as a signal, or the high tension wire for that matter, since the spark advances as rpms go up?

 

No, it shouldnt, the spark "count" always stays the same (1 per rev), and the only thing the advance does is set the spark a bit sooner. This sould have no bearing on the tach, as all the tach does is count pulses per second to give you an RPM value.

 

yep its just the speed changes

16/sec at 1000 rpm to 166/sec at 10000 rpm



You'll need a gauge that 'thinks' its reading from

a single cylinder 2 stroke or at least a wasted spark system

otherwise it might start doing some arithmetic.

A true tacho will just display the input frequency but some,

depending on where and how they get the signals, some will

multiply or divide the output.

 

I would hazard to guess (anyone who KNOWS the ignetek unit can correct me if Im wrong) that since ignetek set the system to work on these bikes, they have probabaly taken the wasted spark into consideration, and it may be software selectable

 

It is software selectable

I KNOW I looked