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Motorcycle Repair/1979 honda cx 500



i have a 1979 honda cx500 custom my problem is i was riding along the highway and suddenly then engine started to die off naturall i thought it was low fuel cause i had been riding for quite some time until i flipped the petcock to reserve and nothing another rider had stopped and asked if he could help and with no sucsess i sat on the side of the road until i could get her home thats where i found that i had no spark on either cylinder so i changed the spark plugs hoping it was the cheap luck i have a spare cdi box so i tried that...nothing im at a loss the spark plug boots are new on both sides is there "points" on this bike or is there somoter options? the coils look fine no cracks in them so im lost if you can help it would be appreciated

thanks Adam


Hi Adam,

The CX500 uses a CDI ignition system which is unlike most other
Honda street bikes which use a TCI or transistor controlled ignition.

If you have no spark on either side then your ignition pulse or trigger
coils might be okay. That means you are likely looking at a stator
CDI charging coil problem. There are two coils on the CX500.
One is for low speed and pne for high speed output.

The low speed I believe is a blue wire and the high speed
is white.  In an situation where you cannot repair the bike
immediately the white wire can sometimes be connected
to both blue and white CDI wires to power them.

If you do this cut the blue wire coming from the stator to
the CDI and then run a jumper from the white over
to the blue wire going into the CDI unit.

This is not ideal but might get you running again.

Check your fuses and wiring connectors first to make
sure they are clean and your problem is not just bad connections.

You might disconnect the engine stop switch too just in case
it is grounding your ignition out.

Here is a link to a page that might help also:

Your ignition switch may also have a grounding circuit
to stop the ignition. The most common cause is one
of the stator coils failing however. This is one
of the documented problems with older CX models.

Wayne S

Motorcycle Repair

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Wayne S.


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


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

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