MSefi.com read only forum (Jan.15,2018)

Buildning µS on a KTM 1cyl 609cc engine.
to start with I tryed to use the original VR sensor but got alot of big rpm spikes, then installed a 50k resistor and got rpm and the engine started but idles very bad. Checked the log and could se that the pw sometimes gose down to zero for no reason:S
an that seams to get wors when the engine gets hot.

I think it may have something to do with my past problems with rpm spikes, so i got a 7pin HEI to give the µS a clean square puls.
My problem now is that i dont get any rpm to the µS, but if i check the signal on optoin with the scope can i se a nice square with aprox 2v amplitude. Is the pulse too weak or why dont I get a rpm signal?
The tooth on the flyweel is a big tooth that stretches from 65 to tdc i think, should that cause any problem?

Try wiring the OPTOIN- wire to the HEI module's output, and the OPTION+ wire to VREF. You'll need to swap the Ignition Input Capture setting to make this work but it often gives a stronger signal.

Matt Cramer wrote:Try wiring the OPTOIN- wire to the HEI module's output, and the OPTION+ wire to VREF. You'll need to swap the Ignition Input Capture setting to make this work but it often gives a stronger signal.

Thanks, it wroked

You mean that the signal gets inverted and if trigged on going high befor i should change it to going low to trigg on the same point?
If i trigg on going high (going low after mod?) would that be the edge on the trigger tooth insted of the middle of the tooth if i go with going low? because i have a very big tooth would it be better to get the trigger on the edge of the tooth.

This triggers on the same edge of the tooth but it inverts the square wave signal that the HEI module puts out.

micke265 wrote: Checked the log and could se that the pw sometimes gose down to zero for no reason:S
an that seams to get wors when the engine gets hot.

I think it may have something to do with my past problems with rpm spikes

I was right:)
Started the bike yesterday and it idled more stable and all zero pw disapeard.