Motorcycle Repair: help ,no power , poping, bikebandits, mail list

Question
I have a 79 cx500 , have a problem with no power ,bike will stumble anything over 25% throttle . and at 7000rpms it all comes back all the way to 10,000. the stator is charging the bike ,and it has a CDI unit . If i unplug the stator from the rectifier the bike has nutty power ,all threw the rpm, and full throttle . But now it doesn't charge . if i plug in the stator now i have 14 volts but the power is gone . The ignition is breaking up . any ideas.   Please help

Answer
Justin, the early CX500s had problems with the stators and/or the pulser coils that feed the CDI system. The CDI is self powered, so is not dependent on the charging system or the battery. There was a discussion about a similar problem on the VJMC.org mail list recently. I think one of the pulser coils was dying. There are two different systems used so check with BikeBandits or PartsFish to see what system applies to your bike.  If you can rig up a window tool, like the one that Honda uses to check the ignition timing, you will probably see one side or the other not spark advancing when the stumbling is happening. You will need an accurate test meter and a timing light would be handy, too. Might be a good time to get a shop manual, as you are going to be going deep into this bike, unless there is some kind of odd loose electrical system connection externally that is the cause. Remember that there is a kill switch on the handlebars and the ignition switch is also a factor in the equation. Those switches are grounds to the CDI not an opening of the circuits, like you find on normal battery powered ignitions. There could be some kind of interplay or electrical interference between the two systems on your bike, due to shorts or open circuits inside. That might explain how you are getting different responses when you disconnect and reconnect the stator.

There are some CX500-650 owner's groups on the web, as well. They have troubleshooting assistance on their sites. There were also some problems with the camchain tensioning system, so if you pull the motor to replace stator or pulser coils, check the camchain and tensioner. Prepare to replace the water pump seal and gaskets, when you go in there, too.

Bill Silver