TOPIC:

Well, I was having running problems, and I think I have it down to the carbs. She's puffing black smoke at 4-5K rpm, and runnign badly at idle. I put new spark plugs in, as the old ones were old, and the old ones were all carbon fouled. She ran great with the new ones for about 10km and then started having the same issues. I'm pretty sure its carbs, I have a new dyna-s that seems to be firing great until the plugs got fouled. Any suggestions?

Check these things, is your air cleaner clean? Can you measure your voltage at the coil? What is it?

Voltage at the coil is 9.6V, so i'm gonna re-wire tomorrow, see what happens. Would this cause her to run really rich? I cleaned my air filter tonight too.

9V is right for mechanical contact points at coils

11.8V-12V is needed for electronic ign at coils

Yeah, I've got a Dyna-S now, so wiredgeorge coil mod it is.

I have the coil mod on my web site now under the "coil repowering" link. Sooty plugs are the result of INCOMPLETE COMBUSTION. The main causes are:

1. Poor spark at coils (less than 12VDC)
2. Poor compression (generally lack of valve clearance)
3. Airflow obstructed (airfilter needs changed/cleaned)

The air/fuel mixture MAY be the cause but when folks make the comment... "bike ran great for x miles then the plugs started fouling", this is a good indication that one of the three reasons or a combination are kicking in and not poor jetting is causing the plug fouling. I believe that if the air/fuel mixture is buggered due to inappropriate jetting (WAY TO RICH), the bike won't run good for even 10 miles.

Yeah, so i did it, and cleaned my air filter, and its still going on. I think I put too much oil on my filter though, and I need to replace my float valves (on the way).

trippivot wrote:

9V is right for mechanical contact points at coils

11.8V-12V is needed for electronic ign at coils

On the KZ650's, both points and electronic ignition should have 12 volts at the coils, the 650's don't have a ballast resister.

Not to sound too dumb, but how do you measure the coil voltage? With the key on, engine not running? Which wire?

I have a 78 KZ650B that runs bad when cold.

-T

On my web site there is a coil-repowering article that explains measuring voltage.