Motorcycle Repair: CA95 spark problem, center electrode, plug caps

Question
Hi Bill,
Have a 1966 CA95 I restored.  Ran fine then all of a sudden I have spark on only the right side.  Any thoughts?? Thanks, Doug

Answer
Doug,  check your battery voltage, spark plug cap resistance values. Plug caps should be zero ohms if originals or around 5k ohms if replacements. A bad condenser usually results in random firing of the coil, rather than just dropping one side.

Recheck point gap and ignition timing. The coil is a double ended unit, which has reversed polarity on one plug. One side will jump the gap from center electrode to grounded side, while opposite plug jumps backwards from ground to center electrode. Sometimes it is harder to see that side when looking for sparks.

Replace the spark plugs and look for signs of fuel or oil fouling. If you are using oil or getting some oil smoke from one side, the wet side will foul a plug. If you full rebuilt the engine, the rings may not be seated yet, so engine will use more oil until rings are seated fully. They don't hold much oil, so always keep it full to the top of the two dipstick marks.

Bill Silver