[calypso]

I received the Bandit 1200 coils today. I have tested both of them and I get 3 ohms each on the primary resistance and 35000 and 38000 ohms on the secondary resistance. All seems within limits for the Katana according to the table in the Clymer manual so I will go ahead and fit them....

[Rider4life]

Ok, so I cannot halve only half a coil working. Spark plugs are ruled out as all the testing has been done with the same spark plug. the left coil fires 1 and 3 and the right 2 and 4 so that is as installed and tested. Switching the low tension wires makes no diference to the results (ie 1and 2 still don't fire). The resistance on the low tension side is correct at 3ohms but on the High tension side the result is 1 (ie no continuity). This may be because I cannot get a good earth.

Uh, do some the kats have a different set up for there I4's? because all other manufactures run 1+4, and 2+3 on the same coils. It shouldn't be 1+3 and 2+4 you'll never get it to run right...

[Rider4life]

Cheers BP,

what do you think about using a set of Suzuki Bandit 1200 coils and caps?. I have just bought a set from ebay. Can I damage another part of the ignition system?

Primary resitance needs to be the same or you can do damage to the ignitor box. secondary(spark side) doesn't matter as long as the either the cap or the plug has the right resistance. But generaly all coils are the same.

[Black_peter]

I'm gonna say that if the primary resistance is the same or with in spec the load on the CDI is the same or similar.

[calypso]

With all the swaping around of cables I have forgoten the order of the coils. What you say does make sense it will be 1-4 and 2-3. Otherwise there would be horrendous vibration since both pistons on the same coil travel up and down at the same time.

I guess it is the left coil 1-4 amd the right one 2-3

[Black_peter]

Heres a cool thing I book marked ages ago..

http://www.salocal.com/anim/sohc4-firingorder.htm

[JIMMYD]

Primary Side VOLTAGE

Heres a cool thing I book marked ages ago..

http://www.salocal.com/anim/sohc4-firingorder.htm

Anyone happen to know what the voltage should be at the primary side of the Coils.
That would be the voltage level measured after the igniton (CDI) box and with the wires unplugged from the primary side of the coil?

[md86]

With all the swaping around of cables I have forgoten the order of the coils. What you say does make sense it will be 1-4 and 2-3. Otherwise there would be horrendous vibration since both pistons on the same coil travel up and down at the same time.

I guess it is the left coil 1-4 amd the right one 2-3

http://www.katriders.com/forums/viewtopic.php?t=19778&highlight=coils

[Black_peter]

Re: Primary Side VOLTAGE

Heres a cool thing I book marked ages ago..

http://www.salocal.com/anim/sohc4-firingorder.htm

Anyone happen to know what the voltage should be at the primary side of the Coils.
That would be the voltage level measured after the igniton (CDI) box and with the wires unplugged from the primary side of the coil?

12 volts.. Good luck measuring it though, unless you have an o-scope
or a very good DVM

[calypso]

I fitted the bandit coils today. I had a minor problem with the length of the caps, they are a bit shorter than the Ket caps. Fortunately they fit just.

I pressed the start bottom and it roared up right away. As soon as I heard the noise I knew it was going to run much better. The iddle settled right away, as soon as it warmed up I took it out for a spin. Wow what a difference, the engine revs cleanly through the range, the power is all there. There is a bit of vibration comming trough the seat at around 100mph but I can easily live with that. It has been a few years since I have ridden a 100Hp + bike. I had forgotten how quickly the scnery comes towards you when you start redlining all the way up through the gearbox. I like how it feels really stable and forgiving.

Much fun to be had. Thanks guys for all your help and advice.

[JIMMYD]

Re: Primary Side VOLTAGE

Heres a cool thing I book marked ages ago..

http://www.salocal.com/anim/sohc4-firingorder.htm

Anyone happen to know what the voltage should be at the primary side of the Coils.
That would be the voltage level measured after the igniton (CDI) box and with the wires unplugged from the primary side of the coil?

12 volts.. Good luck measuring it though, unless you have an o-scope
or a very good DVM

Peter I was actually using the cheapest meter I own and I measured about 10 volts on one primary coil side and about 2 on coils' primary side. I knew something was wrong. Isn't this straight Dc voltage without the bike running?
What would an oscilloscope show me that I'm missing?
I obviously have a problem as the voltages don't match, and I would think they have to. I just not sure I'm correct, or what would cause this problem. Seems like the CDI box is the culprit, but that is a $300 + guess

[Black_peter]

Re: Primary Side VOLTAGE

Peter I was actually using the cheapest meter I own and I measured about 10 volts on one primary coil side and about 2 on coils' primary side. I knew something was wrong. Isn't this straight Dc voltage without the bike running?
What would an oscilloscope show me that I'm missing?

Well thats no way to check it..
You have to see if it is:
a. transitioning the voltage, snapping to zero when told to
b. firing both coils

This transition is so fast that you might never see it with a DVM.
What you are seeing right now could be one coil "charged" with voltage and one discharged. That makes sense it has to start somewhere. Once the starter turns the engine, the signal gen senses the crank position and starts the high /low coil to coil changes. What you need to do is to turn the engine over while checking the transition/ switching using a meter with a trap function or an o-scope. The o-scope will show a spike at the voltage change. You can also monitor both coils with the right set up.

[JIMMYD]

I'm measuring the input voltage at the lead wires while they are unplugged from the coils. Without the bike running I must be measuring straight, uneffected source voltage as the signal generator has no effect unless the bike is being cranked over or running.
I would think the voltages levels (measured as described) should be similar or the same at both coil primary inputs

[calypso]

From a practical point of view I would:

Put a spark plug in the cap of one coil lead and crank the engine while making contact with the plug into a metal part of the engine head. Check for spark, then repeat for the other leads on the same and the other coil. Use the same spark plug so a bad plug doesn't send up the garden path.

If you get no spark at all in any of the leads, provided you know that the spark plug is good. You can have a bad kill switch, a bad side stand connector, a bad CDI.

If you get spark in the leads of one coil but not the other. Swap the low tension cables between the coils.
If you get a spark now in the coil that previusly didn't have a spark. Suspect the low tension wires. Trace the wire through the wiring loom to the exit point (you will need a wiring diagram) and do a continuity test. If the wire is shorted you can replace it with an new wire outside the wirring loom. If the wires have good continuity it must be the box.
If the same coil still does not give you a spark after swapping the low tension wires. Does it not give a spark on both leads of the same coil?-> suspect bad coil (replace coil). If only one lead on the coil has no spark -> suspect bad conection between lead and coil or bad conection between lead and cap or bad cap. You can pull the lead out of the coil (while retaining the securing clips) cut a small piece off both ends, reattach, check again. Altough it may be easier to just change the coil.

I am not so hot on electrics but after some head scratching this is the way a tackled mine.

[Black_peter]

I would think the voltages levels (measured as described) should be similar or the same at both coil primary inputs

Why?
Not all the coils fire at the same time so why would they be charged at the same time? Now in a car the coil has its charge anytime the "breaker" (points or signal gen) is on. Then the high tension current is transfered to each cylinder by the distributer. In the motorcycle system there are 2 coils.
One is fired every rotation. One coil firing on a "charged" cylinder the other on the "burned" cylinder. So as a start, one is charged. As the engine cranks the cycle starts. I'm not sure but you might could get the coil to switch by cranking it by hand.