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1979 Honda CM400A no spark

136 Views 3 Replies 3 Participants Last post by  Bill H
Rode perfect on Thursday but wouldn't start on Saturday with nothing happening to the bike in between (it was under a tarp, dry, sunny conditions).
I have been scrambling to find the issue. I checked the kill switch , by disconnecting it but that didn't help. I tested the resistance of the coil and it seems to be well within spec.

What boggles my mind is that I tested the wired from the CDI box that feed into the coil and they produce a voltage when I press the start but somehow this is not translating to a spark.

I tested the resistances according to this post 1978 CB400A Hondamatic No Spark Faulty CDI Conversion and from what I could tell, it was all okay.
This is a picture of the electrical
If somebody is knowledgeable about this bike, I would really appreciate your help.
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The ing system on the A models is Stator to CDI to coils to Plugs. Your test on the kill switch is correct. The kill switch shorts out the capacitor in the CDI to stop the motor. so unhooking it was right . Start at the stator . Do a OHM test on the stator . You cant test the CDI it takes a special meter. If the Stator OHMs are correct and the coils are ok the problem is in the CDI. One question does the neutral light come on when you turn the key switch on ?

Bill H
You need to be in neutral to start automatics...just saying
I asked to check the neutral light to see if the change switch relay is working . The A models starters are not grounded if the motor is in gear and wont work . There is a kick start lock out on the kick starter to prevent the kick starter from working if the motor is in gear. . These are to prevent the autos from starting in gear. So you need to be in neutral to start the A models.

Bill H
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