CDI testing - Missfire at high RPM - Sound is necessary !

[impmad2000]

I have been testing a CDI for a DDKer and thought some of you might find this interesting. It proves the point that just producing sparks is not enough. Your CDI must produce sparks every time it is required to do so.
Watch and more important LISTEN to the following.



The First thing you can hear is the whistle the CDI makes, and a steady tick as it fires a spark plug (Out of sight). I sweep the frequency of the trigger circuit in 500RPM steps from very low revs up to 7500 RPM. As the RPM goes up, so the pitch of the note made by the spark goes up. This is a good CDI.

Now listen to this one...



All is fine up to 6000 RPM, but at the 6 to 6.5K RPM the note goes lower. This is caused by missed sparks. The thyristor that fires the spark cannot recover fast enough and sparks are lost. Hence a High RPM missfire.

A replacement component should have this working properly again soon.
I just need to fix my soldering iron that has decided to give up on me !!

Cheers All
Tim
(No sparks were harmed during the making of these films)

[Ferry Man]

Fantastic Tim.
Fascinating.

I always carry a spare CDI box and black coil.
I've been caught before.

[hot66]

very interesting Tim Great videos

[Ian Gunney]

excellent Tim

can you still get all the parts to fix a CDI unit?

[Barry]

Interesting that you must get your cleaning products from the same place as me: that tacho must have 1/2 kilo of dust on it .

[impmad2000]

Yes, you can still get the parts. Some are equivalents, and some require some adaptation to fit.
Of course some units exhibit different faults, i.e no whistle or Whistle and no sparks at all !!
Dust ! what dust !!
Cheers
Tim

[58A - 71E]

Ahh more of the dark art explained - great Tim, thanks for posting

[Nige]

Brilliant you've made a Stylophone!