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Discussion Starter · #1 ·
Hey everybody -

First time posting here, really lost on what to check next. As my title says I'm having a few issues. I've been trying to first diagnose the no spark.

New spark plugs, not a problem there. Ignition coils are good. Resistor cap are good.

Since all these problems seem to be happening at the same time are they related to a single point that I'm not catching right now? I've been working my way through the trouble shooting guide in my manual but nothing obvious has stood out yet. I did check the CDI using this youtube video -

I didn't have any resistance on the points he instructed to test so it passes? But I'm still not sure what to do next.

Can anyone help me troubleshoot this?
 

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1987 CMX250C AC
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First what year is your Rebel?..
The Year makes a difference as to which CDI pins do what.
 

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1987 CMX250C AC
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3,091 Posts
The video presenter is wrong in his CDI pin out designation when compared to 96 Rebel
I know of No testing method nor have I read of one to directly test if CDI is good or bad.
All testing is done on exciter power supply, trigger pulse, ground, coil, and kill circuits..
if they check out to be within specs the CDI is considered bad.
Font Material property Screenshot Number Document


I am not familiar with CB250 Nighthawk wire diagram.

Being a 96 I would assume it has a side stand safety interlock which provides one of the alternate CDI grounds, the Neutral switch provides the other through clutch/side stand diode..
On the Rebel this is a Green/White circuit which must be grounded for CDI to operate.
On the other hand if the Black/White circuit is grounded the CDI is disabled.
The Black/Yellow circuit connects to coils
Exciter Black/Red circuit supplies more than 100vac to charge CDI capacitor.. At idle using Peak Voltage Adapter with multimeter my exciter is putting out 140vac and it goes up from there with higher RPM.
The Blue Pulse generator circuit puts out just under 1vac while cranking.
Product Rectangle Font Parallel Slope


Earlier method of checking ignition system was to measure resistance of circuits which is far less accurate than peak voltage measurements.. Resistance measurements are not set in stone as several factors can effect readings.
1st gen 85-87 Rebel specs
Font Material property Parallel Number Rectangle


Video presenter copied Honda's common service manual to explain CDI operation
Rectangle Font Line Schematic Parallel


He didn't bother with instructions on methods to test ignition system, and as I have said I have not read anything that indicates CDI can be tested with multimeter..
Product Font Rectangle Line Parallel


I have read a great deal on CDI operation to be able to adapt 2nd gen CDI to my 1st Gen Rebel.
Product Schematic Circuit component Font Rectangle


The Black/White and Black/Red circuits can be reversed depending on year and model Honda
Circuit component Font Line Slope Electrical wiring
 
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Discussion Starter · #5 ·
The video presenter is wrong in his CDI pin out designation when compared to 96 Rebel
I know of No testing method nor have I read of one to directly test if CDI is good or bad.
All testing is done on exciter power supply, trigger pulse, ground, coil, and kill circuits..
if they check out to be within specs the CDI is considered bad.
View attachment 113447

I am not familiar with CB250 Nighthawk wire diagram.

Being a 96 I would assume it has a side stand safety interlock which provides one of the alternate CDI grounds, the Neutral switch provides the other through clutch/side stand diode..
On the Rebel this is a Green/White circuit which must be grounded for CDI to operate.
On the other hand if the Black/White circuit is grounded the CDI is disabled.
The Black/Yellow circuit connects to coils
Exciter Black/Red circuit supplies more than 100vac to charge CDI capacitor.. At idle using Peak Voltage Adapter with multimeter my exciter is putting out 140vac and it goes up from there with higher RPM.
The Blue Pulse generator circuit puts out just under 1vac while cranking.
View attachment 113445

Earlier method of checking ignition system was to measure resistance of circuits which is far less accurate than peak voltage measurements.. Resistance measurements are not set in stone as several factors can effect readings.
1st gen 85-87 Rebel specs
View attachment 113448

Video presenter copied Honda's common service manual to explain CDI operation
View attachment 113449

He didn't bother with instructions on methods to test ignition system, and as I have said I have not read anything that indicates CDI can be tested with multimeter..
View attachment 113450

I have read a great deal on CDI operation to be able to adapt 2nd gen CDI to my 1st Gen Rebel.
View attachment 113451

The Black/White and Black/Red circuits can be reversed depending on year and model Honda
View attachment 113452
The video presenter is wrong in his CDI pin out designation when compared to 96 Rebel
I know of No testing method nor have I read of one to directly test if CDI is good or bad.
All testing is done on exciter power supply, trigger pulse, ground, coil, and kill circuits..
if they check out to be within specs the CDI is considered bad.
View attachment 113447

I am not familiar with CB250 Nighthawk wire diagram.

Being a 96 I would assume it has a side stand safety interlock which provides one of the alternate CDI grounds, the Neutral switch provides the other through clutch/side stand diode..
On the Rebel this is a Green/White circuit which must be grounded for CDI to operate.
On the other hand if the Black/White circuit is grounded the CDI is disabled.
The Black/Yellow circuit connects to coils
Exciter Black/Red circuit supplies more than 100vac to charge CDI capacitor.. At idle using Peak Voltage Adapter with multimeter my exciter is putting out 140vac and it goes up from there with higher RPM.
The Blue Pulse generator circuit puts out just under 1vac while cranking.
View attachment 113445

Earlier method of checking ignition system was to measure resistance of circuits which is far less accurate than peak voltage measurements.. Resistance measurements are not set in stone as several factors can effect readings.
1st gen 85-87 Rebel specs
View attachment 113448

Video presenter copied Honda's common service manual to explain CDI operation
View attachment 113449

He didn't bother with instructions on methods to test ignition system, and as I have said I have not read anything that indicates CDI can be tested with multimeter..
View attachment 113450

I have read a great deal on CDI operation to be able to adapt 2nd gen CDI to my 1st Gen Rebel.
View attachment 113451

The Black/White and Black/Red circuits can be reversed depending on year and model Honda
View attachment 113452
The video presenter is wrong in his CDI pin out designation when compared to 96 Rebel
I know of No testing method nor have I read of one to directly test if CDI is good or bad.
All testing is done on exciter power supply, trigger pulse, ground, coil, and kill circuits..
if they check out to be within specs the CDI is considered bad.
View attachment 113447

I am not familiar with CB250 Nighthawk wire diagram.

Being a 96 I would assume it has a side stand safety interlock which provides one of the alternate CDI grounds, the Neutral switch provides the other through clutch/side stand diode..
On the Rebel this is a Green/White circuit which must be grounded for CDI to operate.
On the other hand if the Black/White circuit is grounded the CDI is disabled.
The Black/Yellow circuit connects to coils
Exciter Black/Red circuit supplies more than 100vac to charge CDI capacitor.. At idle using Peak Voltage Adapter with multimeter my exciter is putting out 140vac and it goes up from there with higher RPM.
The Blue Pulse generator circuit puts out just under 1vac while cranking.
View attachment 113445

Earlier method of checking ignition system was to measure resistance of circuits which is far less accurate than peak voltage measurements.. Resistance measurements are not set in stone as several factors can effect readings.
1st gen 85-87 Rebel specs
View attachment 113448

Video presenter copied Honda's common service manual to explain CDI operation
View attachment 113449

He didn't bother with instructions on methods to test ignition system, and as I have said I have not read anything that indicates CDI can be tested with multimeter..
View attachment 113450

I have read a great deal on CDI operation to be able to adapt 2nd gen CDI to my 1st Gen Rebel.
View attachment 113451

The Black/White and Black/Red circuits can be reversed depending on year and model Honda
View attachment 113452
I figured it out! It was actually a bad connection point between my excitor coil! Thank you so much for your help. I wouldn't have circled back to check that if not for your post!
 
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