Honda-SOHC

SOHC.co.uk Forums => Other Bikes => Topic started by: McCabe-Thiele (Ted) on October 02, 2024, 04:00:37 AM

Title: What is a CDI unit on the Superdream models?
Post by: McCabe-Thiele (Ted) on October 02, 2024, 04:00:37 AM

I'm doing some more due diligence reading up on the CB500N Super Dream models - there are lots of references to the CDI unit.

So what on earth is a CDI unit & where does it do in laymans terms please?

Title: Re: What is a CDI unit on the Superdream models?
Post by: Bryanj on October 02, 2024, 04:22:35 AM

It takes the signal from two small coils on the stator and uses them to fire the ht coils for spark, i seem to remember that it is not a true CDI ( Capacitor Discharge Ignition) but a sort of electronic compromise.
I think Ash has disected one and can give more details, i do know that the workshop manual gave testing details BUT you had to have a very specific analogue meter, from memory a Sanwa sp 10 d

Title: Re: What is a CDI unit on the Superdream models?
Post by: McCabe-Thiele (Ted) on October 02, 2024, 04:30:11 AM

Thanks Bryan, I've an acute case of Insomnia that has lasted a couple of days - not normal for me whatever normal is. ;D

Title: Re: What is a CDI unit on the Superdream models?
Post by: Bryanj on October 02, 2024, 05:27:06 AM

Thats ok mate, im at work till 6!
That meter i did have one bought in Yokohama in 75, not sure if i still have it!
There was amother specified meter which had a different set of readings for testing.
Never had a cdi box go bad at Meads only 1 400 generator.

Title: Re: What is a CDI unit on the Superdream models?
Post by: McCabe-Thiele (Ted) on October 02, 2024, 07:06:18 AM

I've looked throught the parts list, I can see the coil, CDI unit, unless I've missed it where are the points or is this built into the alternator unit with its own crank poition sensor?

Title: Re: What is a CDI unit on the Superdream models?
Post by: Johnwebley on October 02, 2024, 08:04:27 AM

Quote from: McCabe-Thiele (Ted) on October 02, 2024, 07:06:18 AM

I've looked throught the parts list, I can see the coil, CDI unit, unless I've missed it where are the points or is this built into the alternator unit with its own crank poition sensor?

The CDI is the electronic ignition



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Title: Re: What is a CDI unit on the Superdream models?
Post by: Laverda Dave on October 02, 2024, 09:58:21 AM

Quote from: McCabe-Thiele (Ted) on October 02, 2024, 04:30:11 AM

Thanks Bryan, I've an acute case of Insomnia that has lasted a couple of days - not normal for me whatever normal is. ;D

It's the thought of buying another project bike Ted😉. I've gone to bed numerous times thinking about a problem with a bike and my brain then wakes up and prevents me from sleeping!

Title: Re: What is a CDI unit on the Superdream models?
Post by: magpie114 on October 02, 2024, 10:03:38 AM

And I thought it was only me that did that!


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Title: Re: What is a CDI unit on the Superdream models?
Post by: Johnny4428 on October 02, 2024, 10:14:42 AM

I’m the same, brain refuses to work at 11pm at night but 2am in the morning let’s get to work!😳

Title: Re: What is a CDI unit on the Superdream models?
Post by: McCabe-Thiele (Ted) on October 02, 2024, 12:48:00 PM

Okay so no points, no crank position sensors, no adjustments, just a box that either works or it doesn't. That sounds like fun trying to work out why it won't start!

Title: Re: What is a CDI unit on the Superdream models?
Post by: Rozabikes Tim on October 02, 2024, 02:32:59 PM

Sensor is on the flywheel that sends signal to the CDI ignition thingy...

Title: Re: What is a CDI unit on the Superdream models?
Post by: Bryanj on October 02, 2024, 03:02:36 PM

It could be called a crank sensor but it is an extra small coil(or two) on the generator stator with a small lump on the permag rotor.
Stator and rotor must be changed as a pair

Title: Re: What is a CDI unit on the Superdream models?
Post by: McCabe-Thiele (Ted) on October 02, 2024, 04:25:24 PM

My mind now boggles at how the advance & retard works - the magic of electronics  continues to baffle me.

I'm still amazed by our Microwave Cooker - I've stared throught that gauze on the door many times - never so much as a hello never mind a tiny, tiny wave. ;D ;D ;D

Title: Re: What is a CDI unit on the Superdream models?
Post by: AshimotoK0 on October 02, 2024, 05:08:27 PM

CDi System different on 250N and 400N models.

The two coils on the stator associated with the CDi are prone to failure but there are people out there who rewind them.

Rex's speed shop do the testing guide attached, attached.

CDi unit itself is a potted assembly,

Title: Re: What is a CDI unit on the Superdream models?
Post by: SteveD CB500K0 on October 02, 2024, 05:12:23 PM

Given that microwave ovens work at 2.45GHz, Ted, I’m really surprised that you’ve never noticed the waves. The wavelength is about 12cm / 5 inches, so there’s no reason you shouldn’t be able to see them.




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Title: Re: What is a CDI unit on the Superdream models?
Post by: Bryanj on October 02, 2024, 05:43:41 PM

Ash, i see they dont give the testing tables for the cdi box, thats the one Honda specify which meter you should use and i remember two tables for two different meters