TOPIC:

I'm helping my brother troubleshoot a no spark condition on his 76 KZ900 with Dyna ignition...what we're up against is a strange drop in voltage when the ignition switch (key) is turned on. The main white wire coming from the fuse box to the ignition switch reads 12.27 volts (same as the battery) with the key off...turn it to 'on', and it drops to 10 volts. Reading at the yellow/red wires on the coils is 9.1 volts. The kill switch was bypassed by a PO, so that's not the problem. Thought I'd turn to the gurus for some direction! Thanks

Your problem is pretty typical of these old bikes. Your answer to how to correct your drop in coil voltage can be found at www.wgcarbs.com/index.php?option=com_con...view&id=12&Itemid=26

Many of us here have done this with good results. Anymore I just do it as a routine thing when I get a new old bike.

Thanks, that looks like a nice mod. However, the drop we're seeing wasn't there last year and is keeping the bike from starting at all. Tonight we'll read resistance across all the handlebar switches - with those switches unplugged, we have no voltage drop. Fingers crossed!

snapdaddy wrote:

Thanks, that looks like a nice mod. However, the drop we're seeing wasn't there last year and is keeping the bike from starting at all. Tonight we'll read resistance across all the handlebar switches - with those switches unplugged, we have no voltage drop. Fingers crossed!

The resistance is very low and difficult to read on bad conections. The problem doesn't usually show up until there is a large current flowing in the connection. The best way is to turn on the power and measure voltage drops across the suspect connections.

The dyna S uses about double the current of the stock system, and even more if you are using lower-resistance coils. Everything must be squeaky clean and solid when using the Dyna S. Any burnt or weak-looking wire in the path to and from the coils should be fixed or replaced.