Ref/Sync Issues - Ducati

[mick41zxr]

Ok managed to get it to catch, you can see the ref/sync transform as it does.

Duc916-start capture

Duc916-Start.JPG (437.26 KiB) Viewed 9735 times

Now since replaced the sprag & it makes world of difference.
Thanks for your help.

ducati-916-start2.rsc2

Duc916 ref capture

(64.45 KiB) Downloaded 831 times

[Auto Sport Elect]

Good to hear.

Still something strange in the sync pulse on cranking but it goes away once it runs.

Good luck with your tuning

Glen

[AdamW]

Im with Glen here, something very weird going on here. I initially thought "kick back" but really the only way you could generate a pattern like you see here with the cam occurring 4 times as often as it should would be for the engine to do a full 360 deg backwards just after the cam tooth had passed the sensor, then change direction again, forward for 360, etc... Seems unlikely the starter clutch would slip that much.

Its pretty hard to come up with a logical explanation for what you have, but here's another couple of thoughts without knowing these engines:
Is there any possibility the cam sensor or cam trigger wheel has come loose?
Could you temporarily power the starter motor from a separate battery? - My thought here is if there is a bad ground or similar you could potentially get some starter current passed through the 0V when there is an inductive kick everytime it goes past TDC. Your ref/sync looks too clean for this to be a real possibility to me in this case but still something I would try.

[mick41zxr]

Thanks Adam,
It finally came down to a bad starter clutch.
They are a sprag bearing type in this motor, I think it had enough to get through the compression stroke of the first cylinder but started to slip against the compression of the second & rocked back. This is right at the sync sensor position, giving the odd sync signal.
Since replaced the bearing & starts every time now.
Got tacho up & lambda wired in with a few base pulls on the dyno.
However I will follow through Glens suggestion of building a flywheel with additional ref teeth as it does hunt a little on idle. Maybe an M130 will solve that with its idle targeting routine.
Regards,
Michael