Pulser-Less CDI Units - How do they work?

[IT400C]

I've just recieved one of these today:

http://www.rexs-speedshop.com/epages/es143131.sf/en_GB/?ObjectPath=/Shops/es143131/Products/DT3-PL

It's a new CDI unit (with a modern style curve) from the UK for the DT360A/400B-C, MX400B, YZ400C and IT400C, but the trick part is that it works without a Pulser Coil.

The Pulser coils on these bikes are notoriously fragile and incredibly hard to locate NOS, so GBP 110.00 (including shipping) for a new CDI that does away with the need for the Pulser coil seems incredibly good value. 

Especially when you consider that NOS Pulsers alone usually go for $200 - when you can find one!

So all you electronics guru's out there - how would it work?

I'll be fitting mine this weekend..

[pancho]

 Don,t  know technical details but it is probably triggered by the instant change in polarity as the flywheel magnet passes over the coil.

[IT400C]

Don,t  know technical details but it is probably triggered by the instant change in polarity as the flywheel magnet passes over the coil.

That makes sense - the one change you have to make to the stator plate is to extend the slots by 6mm to get the timing correct.  They do include a nicely detailed drawing showing what to do - or they'll do it for you if you send them your stator plate..

They'll even mount the new CDI internals into an original CDI box if you send them one to retrofit.  That way you can keep your bike looking original.

One of their emails also stated they'll soon have new stator plates with the correct timing slots available soon too - so you wont even have to adjust your own stator plate.

[curly001]

If it come from Rex's speedshop it will work as stated. Marcus started out making new& improved(reliable) ignitions for yammy 500 singles and has gone on from there.

[Lozza]

Interesting I would like to see the schematic. Do they have a ignition graph is the paper work?

[IT400C]

Interesting I would like to see the schematic. Do they have a ignition graph is the paper work?

No ignition graphs in the paperwork...

[mitch75]

This is a smart solution. I am guessing the it uses the source coil as a pulser coil also. Just think of the source coil as a big pulser coil.
Using a AC sine wave produced by a magneto and a reference voltage (say 5 volts) to trigger pulse.

[IT400C]

This is a smart solution. I am guessing the it uses the source coil as a pulser coil also. Just think of the source coil as a big pulser coil.
Using a AC sine wave produced by a magneto and a reference voltage (say 5 volts) to trigger pulse.

Yeah, sounded pretty good to me.. 

I've got heaps of bikes that this would fit (IT400C's coming out of my arsehole, + an MX400B), and while the pulsers are all good on my ride bikes, and I do have a stockpile of NOS Pulsers ready as required, I figured it was worth trying one..

And definitely worth buying one to support someone prepared to think outside the box and make something so useful for the old dungers..   

[pancho]

 There is a business in Sydney called Atom Electric  which makes locally designed and innovative garden care equipment (lawn edgers and the like)
.
 Years ago they developed a small electronic switching device to eliminate the contact points in both 2/ and 4/ lawn mower engines which worked well and is reliable. This interupted the primary circuit (same as points do) but triggered by the polarity reversal as the so called 'edge gap' is passed.
 
At one stage after talking to a tech. from there I fitted one to my XT slider which appeared to work as well as the original but without points.
 However subsequent mods to my ign. set-up work better for me.
cheers pancho.

[brent j]

I've tried a couple of those ATOM units. They gave a massive increase in low-mid range torque but didn't seem to like to rev.
They will accentuate any faults in your ignition system and seem to let the starting timing wander a bit.

Mine got so bad it would kick back and then made the motor run backwards for four or five strokes by sucking unburned fuel from the exhaust.

A Yamaha 500 running backwards and DRIVING the kick start upwards is far worse than a kick back as they then truly break and/or bend kick start levers, knuckles, gears and ankles.

[Lozza]

This is a smart solution. I am guessing the it uses the source coil as a pulser coil also. Just think of the source coil as a big pulser coil.
Using a AC sine wave produced by a magneto and a reference voltage (say 5 volts) to trigger pulse.

That's what I was thinking, that they had a way of exciting a 0-5v trigger pulse, rather than any polarity cahnge. I think the slotting of the stator is a work around but still very tricky stuff. No DC/DC ignition but all good if it gets your old scoot up and running. 

[Andrew L]

How did it go was there any improvement, did it take long to set up, looked at getting one myself not long ago would be keen to know how it ended up.

[IT400C]

How did it go was there any improvement, did it take long to set up, looked at getting one myself not long ago would be keen to know how it ended up.

Sorry, got dragged in to work on the weekend and didn't get a chance to fit it..  this weekend..

[OverTheHill]

story about running backwards. Have seen a few bikes do it over the years with the inevitable damage if kick start touched. Recall back in "68 when JN Roberts was down here on a Husky & his started with a kick back & ran backwards on the line [albeit hairy] gave it the big rev to clear it then dropped the clutch & shot up the tank [ouch]. Think it actually did it from running slowly then backfired & started backwards rather than kicking back when starting in hind sight.. Not sure if were cdi or points in those days [suspect points]. Was funny at the time. Back in my bsa bantam days i told dad i had it running backwards [didn't believe me] so went down to the same hill & started it again [on roll back] & rode it all the way from back of the farm to show him. Things we do aye!!. One more thing, Orange AG175's [points model before the very last orange that had cdi] [i think!!] had a diode on the orange wire just before the secondary coil to stop the possibility of running backwards--could kick back but not carry on a such.

[Andrew L]

No worries look forward to your thoughts on this mod.Cheers Mav