Topic: Use CB500 coils for a CB650 engine/ignition?

[cub]

I bought a CB500 last year where they had change the engine to a '81 CB650 in the golden year of 1988. It's the one with CV carbs and CDI ignition. Now I have trouble starting it and a weak spark and I'm thinking about replacing the ignition coils.

Apparently they changed the engine and most of the ignition system, but the ignition coils seem to be from the original CB500 bike. Are the coils for CB500 and CB650 similar, alike or very different? The bike has run with this setup since 1988 so at least it's working. But should I replace the coils with CB500 or 650 coils? Could I damage something by installation CB650 coils? Do I need CB650 coils to get more juice to the sparks? Or does it not matter at all?

The price tag is quite different though where the CB650 coils are twice as expensive as CB500 (if I buy them here in Sweden).

[Einyodeler]

The 500 coils are 5 ohm and were designed for a point breaker style ignition ,you`ll need to get the later style 3 ohm coils to get the most out of your CDI ignition.Coils rarely go bad so you could look for used CB650 or CB900 coils which also have the removable plug wires unlike the 500`s which are moulded in.You`ll definitely have better spark then.