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Motorcycle Repair/1979 HAWK CM400

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Question
WAYNE, I'M STILL PLAYING WITH THE CM400 HAWK THAT HAS SPARK ON ONE CYL. ONLY. I CHANGED THE COIL AND PLUG WIRE ENDS AND PLUGS. IT STILL ONLY RUNS ON ONE THE RIGHT CLY. IF I MOVE THE WIRES AROUND IT RUNS ON THE LEFT ONE.CARBS ARE SPOTLESS AND IDLE CIRCUTS ARE CLEAN. IF YOU TAKE IT OUT AND POUR THE COALS TO IT IT SEEMS TO PICK UP THE DEAD CYL FOR A TIMEE BUT WHEN YOU BACK OFF IT WON'T PICK UP AGAIN. THE EXHAUST PIPE COOLS OFF TO THE TOUCH AND STAYS THAT WAY. SOMETIMES IT WILL BACK FIRE A LITTLE OUT OF THE COLD CYL. AND THE NOTHING AT ALL.CDI? OR AM I MISSING SOMETHING. THIS HAS A DUAL FIRE COIL ON IT.

Answer
Hi Mark,

If you decide to try a new CDI box then the stator can
be checked with these directions from CDI Magician.

These tests are done with the wires cut from the CDI box
and on the wires leading to the stator coils in the engine.


Before installing the new module examine the condition of the Stator and Coil with an Ohm meter.

   Use a multimeter,   and set it to measure electrical resistance in Ohms.  

  Measure the resistance of pairs of wires that have been cut.


Measure the resistance between the Yellow and Green wires.

The Yellow and Green wires being measured will be coming out of the spark plug coil.  

         The resistance should be less than 1 Ohm.


Measure the resistance of the Pink and Green wires.    

 The Pink and Green wires to measure will be going into the bundle that

goes along the frame and eventually to the stator.   

         The resistance should be about 135 Ohms.


Measure the resistance between the White and Blue wires.   

These wires to measure will be going along the frame and eventually to the stator also.      

         The resistance should be about 85 Ohms.   


Measure the resistance between the Brown and Light blue wires.

These wires to measure will be going along the frame and eventually to the stator also.     

         The resistance should be  about 207 Ohms.


If the stator tests out close to these figures then a new CDI box might
be your fix. Available on ebay for about 90-100 dollars from CDI Magician.


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Sometimes it seems like strange things can happen to bikes but
usually there is some explaination for it.

Often it is hard because older bikes are harder
to find parts or the parts are expensive such as the CDI or ignitor unit.

At this point it could be any of the ignition pulse coils or
CDI but this is what I would do.

If it won't fire on the keft and starting fluid doesn't make it fire
then we can assume the spark is at fault.

The ignition is a bit complex on these bikes so you have
two options. One is find a complete lower coil assembly
and CDI used or try to test the lower coils and CDI for faults.

There are a bunch of tests you can do but if they do not give you
any clues you may be back to trying substitutes.

Go here and see if you can get the manual (free)
http://www.mediafire.com/?cnkmdznfjgz

Go to page 16-1 and follow it down to check the ignition system ohms.

Hopefully something will test out incorrectly to give you some clues.


WS
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Wayne S.

Expertise

Licensed Motorcycle Mechanic, Knowledge of motorcycles from 1960 up, Japanese, British and most other brand motorcycle repairs.

Experience

Worked for Yamaha, Honda, Suzuki, Kawasaki British: Triumph, Norton, BSA Other: Most Scooters and Mo-Peds

Publications
Canadian Motorcycling magazine article

Education/Credentials
Licensed Motorcycle Mechanic

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