Coils & Spark

Some background and a few questions. Feel free to bark at me and tell me I have no clue what I'm doing. :dry:

'80 KZ1000 LTD

Bought it last summer, had spark and carb problems (someone lost the main jets and put the carbs back on the bike!) It was kinda hard to tell exactly if the coils were bad because there was so much raw fuel being dumped into the cylinders that the plugs were getting saturated to the point they could not fire.

At the time I really wanted to get this bike rolling, so after a looking the coils (the casings were splitting and looked like hell) my kneejerk reaction was to go ahead and replace them, and at the same time get the main jets. Someone suggested Accel coils, and with doing this I also purchased a set of jets just a hair larger than the stock jets to deliver more fuel, nothing high performance. Currently, I have problems with 2&3 firing - when totally cold, whereas I need the choke on to start up, they fire up, and run great until I stop and shut down. When I shut down, more often than not, I lose 2&3 as evidenced by the lack of spark on timing light, and there's no getting them back until it cools down.

Is this spark plug glazing? Why is it always 2&3? Have I just created problems with the hotter coils? Is there a suggested spark plug for stock vs hotter coils?Maybe I should buy the Green Coil Dyna set on Z1enterprises, put some stock size jets back in the bike and be done with this?

Thanks,

RJW

I am no expert by no means , You know what an expert is ? (an ordanary person giving advise online )(: Anyway ,, I would look more on the lines of something getting hot then not working ,,

You can't solve that many issues at once.

How did you come to choose the coils you did? I'm thinking that your bike has electronic ignition. Am I right? It's very important that you match the impedance of the new coils to the stock units. Did you consider primary impedance? Even if your bike has points the impedance is still a big deal.

Since cylinders #'s two and three run off of the same coil and you say that you have new coils. I'm betting that for some reason the power to that coil is getting interrupted. Either your electronic ignition is cutting out or you just have an intermittant connection to that coil.

KZCSI

How about the pick up coil .. could it b getting over heated due to less resistance in the coil ??

Pickup coils will not be affected by spark coils at all.

You can use spark coils with higher resistance without hurting anything. (Impedance is NOT the same resistance, by the way. We measure the resistance.) The resistance determines the final current draw on the circuit. If the resistance is too low, it draws too much current. This hurts the points or the electronic module, but not necessarily the spark coils. Modern motorcycle coils seem to handle 100% dwell pretty well. They may get hot which is bad in the long run, but not immediately. Either way, stock ignition only runs from 120 deg to 180 deg dwell.

If you are sure you are not getting spark at all on 2,3, then it can be the coils, pickup coils, ignition module, points, or wiring. You have to eliminate them by swapping stuff.

There's a few threads that explain the process nicely but the search feature really blows so I guess it's going to have to go the hard way.

First thing is to swap the spark coils and see if the problem follows the coil.

Hey Loud,
You're correct I should have said resistance instead of impedance.

Thanks for the correction.

KZCSI