OT-Honda ATV No Spark Troubleshoot

GarryinNC

Well-known Member
I am working on a neighbor's Honda TRX300FWS (1995) ATV. When trying to start it with the electric starter, it has no spark until you let off the starter button. It will then spark as the engine come to a stop. If the piston is in the right position, it will fire and run as this happens. Once it starts, it runs perfectly. It will start with the kick starter, usually on the first kick.

I know these are magneto type ignition. I even started it with the battery disconnected, using the kick starter. I have seen battery ignition vehicles do this when the starter was drawing a lot of amperage. On these Hondas, I believe the coils for the magneto primary current are located with the regular alternator coils in the crankcase.

Any ideas will be appreciated.

Thanks,
Garry
 
Can not say on that but most motorcycles I mess with have a coil that is powered with the battery and yes if the starter pull to many amps will do that.
 
I had the same problem recently on a Kawasaki ATV. Turned out to be the CDI box. We were out of town for a week and my son left the key turned on which drained the battery and apparently fried the box. Turning the engine over and would have no spark until a second or two after the engine stopped turning, then get a spark. If it ever fired it would then start OK for a while, but after sitting for a few hours no start.

If this is the problem you can pick up a new CDI module for about $60 on Amazon.
 
You already tell us its a Magneto instead of a battery powered ignition, so no sense in discussing low voltage coil problems. HOWEVER if I recall (its been a while so no warranty) a bad or weak stator (are you experiencing any other problems??) can affect the spark and if it happens to have a CDI Ignition, the CDI unit itself OR again a stator problem may cause your symptoms.

Sorry not much help on that ATV, the above is about all I recall, CDI or Stator problem?

John T
 
Thanks to everyone. I signed up on a Honda ATV forum and 3 or 4 replies on there said it is the CDI box(module), as did Mashbox and John T. They said it is common on the older Honda quads. I found one aftermarket for less than $60.

One reply said that the bypass circuit in the CDI box fails. The box is sealed, and not serviceable. It still puzzles me why a magneto type ignition would do this. Separate circuitry from the battery/starter side of the system.

I hope the new box fixes it. Thanks again.
Garry
 
I am pretty sure that is like others I worked on in that era. It's
not a magneto.

Hence the box which electronic. The wiring diagrams I have seen
only show a trigger coil that the box reads. They also have a
feed from one of the charging coils. I am not real sure why.

I had one with a wiring problem and it runs on an old chrysler
ignition box and an automotive coil. I got tired of fighting it.

RT (a big 2 cents worth)
 
Gary, regarding your question

"One reply said that the bypass circuit in the CDI box fails. The box is sealed, and not serviceable. It still puzzles me why a magneto type ignition would do this. Separate circuitry from the battery/starter side of the system."

I DONT KNOW THE ANSWER

However I'm going to think out loud here as to possible reasons why..........

Even though a typical Magneto like on our old tractors has its very own magnetic rotor and stationary coil into which voltage is induced by the rotating magnet, PERHAPS?? the circuitry on your Honda uses the stronger stator coil windings (probably more energy then a single magneto) to pump current into the CDI box which charges the capacitor which a signal then causes to discharge a current spike into the ignition coil which produces the spark?????????????

I say that because I faintly remember something about a bad start can cause a weak spark????

Maybe some of the more current ELECTRONIC gents like JMOR and Soundguy and Bob and drsporster and others have some insight into it BECAUSE I SURE DONT (Im more into electrical then electronic) just thinking out loud here........

John T
 

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