Quote:
Originally Posted by burner
Interesting about your tacho, going bonkers when you switch on. Does this mean you haven't got that functioning at all?
A clever mod, can't wait to see some detailed pics.
|
The tacho and the temperature gauge were the only likely problem areas with doing this swap, the early bike has no temperature gauge as such, just the high temp led, therefore as the later bike does have a gauge we knew that was likely to be some circuitry missing from the electrcal system of the early bike, however as details of the internal circuitry are hard to come by, it wasn't possible to check this first. It's most likely that the early clocks have a simple circuit connected to the sensor on the 'stat housing, which is a variable resistor, the resistance of which is affected by temp, once the resistance changes to 'x' figure, then the temp led lights, all the relevant circuitry, (not much), is housed in the clocks. On the later bikes the wire that connects to the gauge comes from the ECM under the seat, so it's obvious that there is something in there which takes the temp sensor output and turns it into a guage reading, we don't have this so it's unlikely we can make that work without a better understandng of the internals of the ECM *.
On a more conventional system the tacho has a current supply and one connection to a convenient point on the low tension side of one coil, simply put the tacho counts the pulses, (1 per spark), and deduces from that the engine speed, no need for any other components necessary, all self contained, on the injected models however the tacho is also connected to the ECM, having had a look at the circuitry of the later tacho, there's nothing obviously unusual about it, but it doesn't work properly when dirctly connected to the earlier bike, as yet it isn't possible to know why, I suspect that simply the trigger output voltage from the ECM is at a different level, whether this is higher or lower, or for all we know yet instead of one pulse per spark it could be one for every 6 2/3rds sparks.
Anyway BillyC wants to bring his bike round for a small job to be done and he has very kindly offered to let me test his bike and find out what's happening with the electrical system of a late bike and what we might do about it.
So there might be more on this when we find out what happens in injected bikes 'leccy systems.
* Anybody got a K3/4 ECM they want to let me break? No...what a shame.
