Motorcycle Repair: 1976 cb 550, cb 550, plug caps

Question
firing order for 1976 cb 550 and 2&4 are firing but 1&3 are not

Answer
It sounds like you have the wrong wires on the plugs, for starters.

Coils fire both plugs at the same time, one coil for 1-4 cylinders and one coil for 2-3 cylinders.

Test the coils for primary winding resistance... somewhere about 4.5 ohms, both coil sets should be very close to the same readings.

After that, test the spark plug caps for about 5k ohm resistance. Make sure that the caps are screwed into the plug wires tightly.

Clean and adjust the point contacts so they have about .014"-.016" gap, then set the backing plates so the 1-4 points just open at the 1-4 F mark and the 2-3 points open at the 2-3 F mark. Best to check full spark advance using a dynamic automotive timing light when the engine is revved up to about 3k rpms.

If you see any excessive point arcing, then the condenser for that set of points may be failing.

Always start testing with a fully-charged, load tested 12v battery.

Bill Silver