Topic: Pulse Generator or Ignition Coil

[braincube]

Hi guys! It's been awhile!

I'm still struggling through some work on an '82 CB650 that won't start. I thought it was the fuel system, couldn't troubleshoot it, got impatient and brought it to a shop. They notified me of no compression in two of four cylinders - and that it needed a full top-end rebuild.

So, I did it myself. The full top-end rebuild - everything went really well. And still, the motorcycle won't start. Carbs are getting fuel, but the spark plugs are firing weird. Spark plugs connected to cylinders 2 and 3, connected to the RHS ignition coil, fire repeatedly (normal). Spark plugs connected to cylinders 1 and 4, connected to the LHS ignition coil, fire once and then remain dead. Could the problem be the pulse generator? I noticed one of the black plastic units of the pulse generator has unseated from the metal plate.

How do I test for failure of the pulse generator or failure of the ignition coil?

[dave500]

got a multimeter?

[braincube]

Yeah, now how do I use it?

[KiefRichards]

Yeah, now how do I use it?

You need something like this

[braincube]

Ha!

I meant - what measurements should I be testing? What values should I see?

I (generally) know how to use a multimeter..

[KiefRichards]

Ha!

I meant - what measurements should I be testing? What values should I see?

I (generally) know how to use a multimeter..

Is there a component test in the manual for it?
Post a wiring diagram of the ignition system... Then we can walk you through it

[dave500]

measure the ignition and pulse coils with it.

[zeech]

CDIs could be fried. 650s can be a pain. I got rid of them all together, but I also completely rewired my bike.

[scottly]

Could the problem be the pulse generator? I noticed one of the black plastic units of the pulse generator has unseated from the metal plate.

Do you mean it is just flopping about? It should be held with 2 screws to the plate.

[SOHC]

CDIs could be fried. 650s can be a pain. I got rid of them all together, but I also completely rewired my bike.

Curious How did u get rid of the CDI's?

[trueblue]

Well technically they aren't CDI units, they are essentially pulse amplifiers. The ignition system on the 650s are little more than an electronic point system. Very basic in the world of electronic ignitions. If I remember correctly to test the pulser unit it is as simple as checking the resistance between the two wires that go to the unit.  If you have one pulser that is loose you have likely found your issue before you began.  They need to be held firm. There is no tolerance for movement with these parts.

[braincube]

Alright - thanks a ton, guys.  These replies are all very helpful, particularly the stuff about the CDI and loose pulser generator. I'm gonna go in there tonight and check all of these things out, then report back ... wish me luck!