CB400 cdi

You might be getting mixed up as to the figures to expect?

You are correct that Honda give 2 sets of figures for the CDI tests- and yes they refer to 2 different testers to use. Remember these were back in the old analogue tester days, and the Honda dealer would have either of these testers in his workshop and technicians that probably didn't understand what they were testing. The SANWA meter was scaled in divisions of kilo-ohms and the KOWA meter was scaled in divisions of 100's of ohms. This is the only reason there are 2 sets of resistance figures in the CDI tables- one for each make of tester. So in general the numbers to be read off on the different testers differ by a factor of 10- although the same resistance. I actually have the KOWA tester from an old Honda dealership- it's a pretty basic, inaccurate bit of kit.

The resistance tests for the generator as you say also appear to have 2 sets of readings- but this is for a different reason. As these were much lower expected resistance readings a third Honda tester was mentioned- so just one meter recommended. But there is a side-note in the manual that the values in parentheses (brackets) are to be used for a different generator type used in some bikes, identified with yellow paint on the mounting screws? Engine numbers are also quoted- seems the later bikes.

So if you work out which generator types you have there you can ditch one set of numbers as far as the generator goes. It's still a concern that even then you are out of spec for most of them, but you obviously are not using Honda Tester 07308-0020000- probably a modern DMM? This is why we need to measure known good generators and make up our own known set of good figures....

 For your "collective info" in free space for all to see.


This info was gathered some time ago, several months if not more, when the oe stator died on the lads 400, some time after the oe cdi died and REX unit fitted. Rex unit still working great, very very easy starter ( it was before ).

Will try and gather all 400 ign threads in one place for easy reading ( so i can remember where the stuff is mote like )

Resistance values when engine cold and ign system stator connection blocks disconnected from cdi.

AC Volts of course taken from connections connected via probe, cheapo dmm.

Thought I had lost this post due to poor internet connection yesterday, its raining today, so water must help?!


Pink to earth, 131 ohms. 5.2vac at idle, 15.9vac at 4k revs, 16vac at 6 k revs.

White to earth. 331 ohms 50vac @ idle, 30vac @ 4k revs, 22vac at 6k revs.

D/Blue to earth, 356 ohms 50vac @ idle, 32 vac @ 4k revs, 24 vac @ 6k revs

L/blue to earth, 110 ohms, 0.38vac @ idle, 0.84vac @ 4 k revs, 1.25 vac @ 6k revs

Brown to earth, 131 ohms, 0.4vac @ idle, 0.6 vac @ 4k revs 0.9vac @ 6k revs.

The d/blue wire coil, the lowest mounted on the stator, seems insulation breaking down at revs, looks burnt. This coil was burnt out on the oe stator, so engine would not rev over 6k revs, due to insufficient cdi capacitor being charged.

Second Hand stator fitted.

As above......

Pink to earth, 130 ohms, 5.6vac @ idle, 15vac @ 4k revs 15vac @ 6krevs

White to earth, 341 ohms 59vac @ idle, 62vac @ 4k revs, 54vac @ 6k revs

D/Blue to earth, 426 ohms 98vac @ idle, 156vac @ 4k revs, 173vac @ 6k revs

L/Blue to earth, 113 ohms, 0.45vac @ idle, 0.67 @ 4k revs, 0.75 @ 6 k revs

Brown to earth, 94 ohms 0.26vac @ idle, 0.45vac @ 4k revs 0.54 @ 6k revs

The engine revs well now, but ign advance is jurky, advances immediately to about half way just over idle speed, then transition to full advance at about 4k revs.

The system seem a bit advanced ign wise, slightly over advanced at idle and at full advance, but it revs all the way to the red line now.

This unit is not perfect but data shows misfire due to insufficient charge coil energy from the other 2 stators,

Will home rewind the d/blue dead coil on oe unit as I have the correct size wire, know the approximate number of turns and coil dimension.

The brown wire to the alloy outside flywheel sensor, I will re wind with the same wire and test its output at idle speed ( plugs out cranking ) , adjust accordingly and hopefully be able to use.

The spare stator , I will rewind the dark blue coil on that and test/use.

Hope this helps you.

ps ht coil yellow wire, connected to coil, engine cold..

idle 0.65 vac 1.38vac @ 4k revs 1.76vac @ 6k revs.

will do this same test on "good stator" and report back.for your "collective info" in free space visible for all to see.

3249 is YHV's frame from memory.

Hi Crouchy.
This is getting interesting or more confusing, not sure which. If you look at the tables I created for my 4 generators, the only one that has all readings in spec is coil set 4. This uses the Honda values that are not in parentheses, all of the other stators have at least one out of spec reading. The ambient temperature was about 12 degrees C when I took the readings.
I use a Fluke multimeter, not sure which model, but feel sure most modern multimeters would give accurate enough readings.
One thing I did find though was that heating the stator to about 60 degrees C caused the green-white wire resistance on coil set 2 to rise from 297 ohms to 320 ohms. Obviously temperature will make a big difference to the resistances.
Very strange that I have 3 generators where the green-white resistance is low, yet the 2 that Rich has, are both within spec on the green-white resistance and according to his post, the engine was cold.
No more thinking tonight it's getting late.
Mike.

Agree 100%. As you say even 10 shorted turns would have very little effect on the resistance reading, but would make a big difference to the ouput of the coil. As someone on another forum said "scope it don't grope and hope it".
Mike.

One thing I never got round to doing was putting a strobe on my SD400. I had no running issues, but always meat to check it anyway.
Unfortunately my SD is 1000 bits at the moment, I have at last started the restoration.