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hi,restoring a 1980 kz1000 ltd, its been standing for 6 years, after thourough carb cleaning and fresh fuel its still running badly, i now supspect a weak/ intermittant spark causing bogging and missing at higher revs when under load.
All cylinders fire and i can see a small yellow spark on all four plugs so i assume the pulse coils and ignitor are fine, and im getting around 11.5 volts at the coils (drops to about 9 volts when running)i think this is high enough voltage- i assume the only things left are the coils themselves, ht leads and caps, are there any suitable tests for the coils that can be performed on a basic multimeter, cheers- mat

battymatty wrote:

hi,restoring a 1980 kz1000 ltd, its been standing for 6 years, after thourough carb cleaning and fresh fuel its still running badly, i now supspect a weak/ intermittant spark causing bogging and missing at higher revs when under load.
All cylinders fire and i can see a small yellow spark on all four plugs so i assume the pulse coils and ignitor are fine, and im getting around 11.5 volts at the coils (drops to about 9 volts when running)i think this is high enough voltage- i assume the only things left are the coils themselves, ht leads and caps, are there any suitable tests for the coils that can be performed on a basic multimeter, cheers- mat

You should be getting 12volts all the time.
You seem to be a prime candidate for the WG coil mod. Go to the KZ INFORMATION tab, click FILEBASE and look for the mod.

Good luck and have fun

spark should be blue not yellow.

hi again, just been checking out my electrics to try and get to the bottom of this, have found that charging system is functioning correctly, but still found that coil voltage is dropping to 9-10 volts whilst running,
i traced back the power supply to the coils to a resistor + heatsink under the tank if i bypass this i get a good 12 - 12.8 volts at the coils and now a faint blue spark (still v. small but better than the yellow one i was getting before)- there is an improvement in running but not that much - still misssing, bogging and backfiring- i have replaced the ht leads, so im hoping a set of replacement coils should sort the problem, however im worried that by bypassing this resistor i may overload the coils- any ideas/ comments , cheers- mat

Do the coil mod as mentioned in a earlier post. The bike will come alive. Roy

Believe me! Roy

Post edited by: roy-b-boy-b, at: 2006/04/23 11:10

cheers roy, i will get onto the coil mod next, first i think ill try running 12v direct from the battery to the coils, to test if it works before i invest in a relay and the extra wiring, hoping this will sort it....

As one who did the coil mod....it's WELL worth whatever the relay and some wire and connectors and solder cost's.
Night and Day difference.......so if you need help when you do it...post up and we'll get ya there....
Goods looking bike...

just tried coil mod- but no change, as i said before 12 volts or near (same as battery voltage) is reaching the ballast resistor and in turn the coils, but with the engine firing this drops to 9-10 volts at the coil - this happens with the standard setup or the mod -both giving a weak spark, if i bypass the ballast resistor i get 12 - 13 volts at the coil and a slightly better spark, however im worried about burning out the coils, why does the resistor drain power when the engine is firing + is there any function to the resistor other than protecting the coils from overload, im still thinking i may have an insulation failure on the coils/ht leads, i may silicone the whole lot this week to find out, again any comments atall greatly appreciated.