No spark on 79 CM400A

Mongeau308

New Member
Joined
May 1, 2026
Total Posts
9
Total likes
8
Location
York Pennsylvania
Hello! Im getting no spark on my 79 cm400a the bike has been sitting for several years. 3000 on the odometer. I replaced the plugs and did an oil change and some other basic maintenance and when i went to go and start it for the 1st time i have no spark. I am getting 1-2 volts from the cdi and my coil and wires and plugs resistance check good. Scratching my head on what else the issue could be.
 
Mongeau308 said:
Hello! Im getting no spark on my 79 cm400a the bike has been sitting for several years. 3000 on the odometer. I replaced the plugs and did an oil change and some other basic maintenance and when i went to go and start it for the 1st time i have no spark. I am getting 1-2 volts from the cdi and my coil and wires and plugs resistance check good. Scratching my head on what else the issue could be.
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The electronics from this era are known to fail with age, regardless of mileage unfortunately. After you go through all the testing procedures, report back your results and either @LongDistanceRider or @Maraakate will help you reach a conclusion about your needs.
 
Easiest test is to disconnect the black w/ white tracer bullet connector going to the CDI. This eliminate the kill switch and ignition switch being the cause.
 
Maraakate said:
Easiest test is to disconnect the black w/ white tracer bullet connector going to the CDI. This eliminate the kill switch and ignition switch being the cause.
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I already did that and still no spark. When removing the case for the stator i noticed a little bit of epoxy was laying in the bottom. So im gonna test that out next
 
Mongeau308 said:
Pictures of the volt meter results?
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You can't measure these tests with a volt meter unless you have a peak voltage adapter OR an analog meter. It will 100% not work with a digital meter so do not waste your time.

I see you are literally 20 minutes from me. I am in Marietta. Maybe I should meet you locally?
 
Yeah that would be awesome man. I can get my hands on a analog ine. I borrowed a snap on fancy meter that might have peak voltage.
 
Maraakate said:
I doubt the snap-on meter has it. Where are you in York? I can't meet you this weekend, but next weekend in the evening would work.
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I can’t pm you since I'm too new of a member. If you send me a message i can give you my number and we can pencil in a date/time that works for you.
 
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