Topic: EI vs CDI

[amitr0]

The points system can be replaced by electronic ignition for the sohc. More modern bikes have/had CDI.

What are the differences between the two? Is EI for the CBs a type of CDI, or the underlying tech is not capacitor based at all? Can the sohc have CDI based ignition?

[TwoTired]

For a description of CDI  see:
https://www.wbnoble.com/WN_articles/CD-ignition-SK.pdf

There used to be a CDI offering for the SOHC4.  I forget the brand (which might be important if still available), it was a good unit, though pricey. I wish I had them on my bikes.  But, the points are still quite useful.

EI is just a replacement of points contact with an electronic switch.  Some actually keep the points for use as a timing trigger.  Others replace the points cam with a different means to tell the switch transistor to cycle on or off.  Both styles eliminate the high voltage and currents that routinely damage the point contacts in operation.  Lots of nuance variations among offerings, I won’t include descriptions of them all. (Small book for that.

Cheers,

[Don R]

  My dyslexia kicked in and I thought I saw "Elvis CD!"
  Gerex the old CD ignition?

[TwoTired]

Ah, Gerex.  That’s what I couldn’t recall. They would be over 30 years old these days.  I wonder if the internal capacitors are still good inside.  I think Scottly had/has one of these.

Cheers,

[Don R]

Ah, Gerex.  That’s what I couldn’t recall. They would be over 30 years old these days.  I wonder if the internal capacitors are still good inside.  I think Scottly had/has one of these.

Cheers,

 

 Thanks,  I picked up a Gerex recently, it doesn't make the whine sound but it makes a bright spark. Terry has an old/new in box one too. Looks slightly wonky in the recommended location near the right rear turn signal.

[scottly]

Ah, Gerex.  That’s what I couldn’t recall. They would be over 30 years old these days.  I wonder if the internal capacitors are still good inside.  I think Scottly had/has one of these.

Cheers,

Actually, my Gerex is over 43 years old now, and still works fine. I started it up the other day for the first time in nearly a year, and thanks to the Shorai battery and possibly the Sta-bile added to the gas back then it fired right up. You can see the Gerex box above the K&N muffler sticker.
By the way, there is a Maverick gas station in Prescott near the Hospital (don't ask me how I know ) that has ethanol-free gas, and another has just opened up at the intersection of Fain rd. and hwy 69, which is only a few miles from me. The last time I drove by, regular was $3.29 and E-free was $3.69. The bad news is that it's only 87 octane. 

[dave500]

CDI was used on a lot of magneto only dirt bikes,the coil is special to a cdi unit,basicly a capacitor gets charged up then unloaded (discharged) into a coil producing a spark,unlike a coil which gets charged up then switched off producing a spark like with points or electronic types,i dont think many road bikes have had cdi from the factory i can think of only kawasaki two stroke triples?most new dirt bikes these days have efi,electric start and electronic ignitions,cdi seems to be way out dated?

[Don R]

 My bike with the Gerex has Cir-cycle coils, I think the later units came with the same ones except labeled Gerex. They appear close to the shape of Andrews coils, but I have no idea of the electrical properties except around 4.5 ohms. I'm curious about what coils can/should be used with an obsolete CD ignition.
 This unit has one of the brightest sparks I've seen, but certainly not like a flash bulb that's described in the vintage ad/magazine article for Gerex.

[Don R]

 Isn't MSD a CDI design? I'm running a really old one of those too. Possibly a 1991 model if it came new on the car. If so, it has sparked a Buick V6 as well as a 567" BBC.
  I googled Gerex and in a KZ forum someone posted there was also an electronic version of Gerex called a "convertible ignition" it used a magnetic pickup and was a non cdi unit in a smaller package. Sounds like the Hondaman unit but using a magnetic trigger. 

[Bankerdanny]

I had a Gerex on my GL1000 and liked it. My bike definitely started and idled better after the install. I seem to recall Jerry Griffin had a Gerex in the boot of his car at Mid Ohio back in 2019 if someone wants one.

The problem with the Gerex is that the CD box is quite large (as you can see in Scott's photo) and it needs to be where it can get some airflow for cooling.

On my 2002 Enfield Bullet I swapped from points to a simple electronic ignition and the change was dramatic. It started far easier than it had with the original points setup.

[Tracksnblades1]

Does anyone know of any 3d programmable
Ignitions with map, tpi, o2 sensors that eliminates
the mechanical centrifugal advance completely?
That are in a conversion or kit form for the sohcs.

I’ve read someone manufactures
A unit adapted or designed and currently
being used on a 82 or 83 cb1100 Racing with “carbs”.
Allowing different timing/rpm maps for
part throttle positions and varying
absolute manifold pressures.
Perhaps racing later this year in Oz…?

[Don R]

 I heard about a holley efi unit being used on a no prep car with a carburetor. I wondered if it also had efi of some sort.