79 KZ1000 ST

I have a 79 KZ1000 ST with what I believe to be a bad/weak coil (or maybe
just the wires) Problem is that the wires are not removable. Now, I like
to tinker, and have considered slowly cutting away the housing near where
the spark plug wires enter the coil, and see how its connected. Has anybody
attempted such a thing? Its mainly out of cheapness, and unwillingness to
drop $150.00 on a new set of coils, if I dont know it will fix my problem!

 

I knew I a guy who bought a Honda CB500 at a yard sale. It had 8 bent
valves from being over-revved horribly and the previous owner had also
cut the wires off the coils, so this guy stuck ordinary sewing pins
into the coils and cut their heads off and slid new metal core spark
plug wires down over the pins.

The wires fell off on the first ride...

But, what does the spark you're getting now look like? If it jumps
1/4th of an inch with a blue spark and does that every other turn of
the engine, you have plenty of spark to fire the mixture (at least at
idle).

What symptoms does your engine exhibit when running at high RPM or with
lots of throttle?

Your KZ1000 ST has electronic ignition with a pulser coil to send a
signal to the electronic ignition box and there is a ballast resistor
hidden somewhere in the wiring harness.

Check that ballast out to see if it's making good connections.

In the 1950's and 1960's cars used ballast resistors mounted on the
firewall in the engine compartment to reduce the 12 volt battery
voltage down to 5 volts after starting the engine. The engine got a
hotter spark for starting, then ran on less current when the resistor
heated up.

So, if you were to buy a stock coil for your KZ1000, you'd probably be
buying a 6 volt coil which would have about 1.5 ohms of primary
resistance, instead of the 3.0 ohms of a 12 volt coil. If you use a 12
volt coil, you need to bypass the ballast resistor. Will the transistor
ignition unit put up with a 3.0 ohm coil instead of a 1.5 ohm coil?
Probably.

I recently saw that www.oldbikebarn.com was selling aftermarket Dyna
ignition coils, but the purchaser definitely needs to know *which*
resistance coil to buy...

 

Aftermarket high-output coils are way cheaper than this and will perform
better. Have a look in some catalogues.

 

What symptoms are you having? I just "fixed" my friend's '79 KZ1000
that was hard starting and stalled under load until warm. We just put
in new plugs and replaced a couple broken plug caps, so that it runs
great now. Have you tried simple stuff like that?

 

If you are cheap, you won't go hacking up your coils without good reason.