Fat blue spark?...

What should a fat blue spark look like? Obviously fat and blue right?

I just checked the spark on my bike using a new outta the box spark plug, with correct gap, grounded to the engine. I left all 4 plugs in the engine while doing the test and just moved this fifth plug from one to the next cap leaving the other three plugged in. The bike started right up on three cylinders during the test, btw.

I had a blue/white spark but to me it looked thin. Just how fat should the spark be? Should it be the thickness of the electrode? If so mine was nowhere near that. It just looked like a tiny arc that ran around the sides of the electrode. Bigger than a carpet charged static electricity arch you give to your friends, but not by much.

If I remember correct last time I looked at the spark on my 1975 boat engine it was much stronger and even made a cracking sound. The spark from my bike didn't make any noise.

My coils are original, along with the wires and caps. Still on points also, but a new set. I have gone thru the electrics and am getting good voltage to the coils, went from 8 volts up to over 12 volts when I went thru everything. So its not low voltage to the coils causing it.

I'm not planning on going to dyna-s and new 3.0 ohm coils just yet. I'm fine with points for now. I see Z1E sells some 4.0 ohm Suzuki coils for $36 each with wires attached. Should I throw a set of those on there?

www.z1enterprises.com/ItemDetails.aspx?i...zuki&item=EM24-72451

Or is my thin white/blue spark ok?

I have run one of those $36 coils from Z1 on my 750 twin for 6 years. Really strong spark, better than my original. Running 30+ year old coils is bad news.... I found out.

I've seen other posts where you said the old coils should be replaced. What problems did you have?

Would you say I have a weak spark using these original coils? Should the spark be more than a thin blue/white spark? I searched but had a hard time finding a pic of what a good strong spark should look like. Before I went thru the wiring and got battery voltage to the coils the spark was orange. So its better but I'm not sure if its a 100% good spark.

I would like to just go to Dyna-S but I dont want to spend $300 on the setup.

I can get these 4.0 ohm coils and some caps for around $80 and stay with the points setup for now. Then someday switch to the Dyna-S and the 4.0 coils should work fine with it. 3.0 ohm coils would probably be better with Dyna-S, but the 4.0 will work right?

Do I need to get a certain type of caps with the new coils? Do they have to be resistor caps? I don't see why I need resistor caps with a points setup? I don't have a radio or CDI in this bike.

74ullc wrote: I've seen other posts where you said the old coils should be replaced. What problems did you have?.

The original gradually failed, got hard to start, ran rough when it was hot. So I bought a "good used" coil and it went flaky after a couple of months. Old coils = waste of my life. Since they "arc down" internally from age, they don't show up on a bench test.

74ullc wrote: Would you say I have a weak spark using these original coils? Should the spark be more than a thin blue/white spark? .

Hard to say exactly what's up over the internet.

74ullc wrote: Before I went thru the wiring and got battery voltage to the coils the spark was orange. So its better but I'm not sure if its a 100% good spark..

Is the condenser relatively new? A bad condenser will make a weak spark.

74ullc wrote: I would like to just go to Dyna-S but I dont want to spend $300 on the setup.

I can get these 4.0 ohm coils and some caps for around $80 and stay with the points setup for now. Then someday switch to the Dyna-S and the 4.0 coils should work fine with it. 3.0 ohm coils would probably be better with Dyna-S, but the 4.0 will work right?

I think it should work with 4 Ohm coils.

74ullc wrote: Do I need to get a certain type of caps with the new coils? Do they have to be resistor caps? I don't see why I need resistor caps with a points setup? I don't have a radio or CDI in this bike.

I'd recommend resistor caps if the coils do NOT have resistor wires. Ask the guys at Z1 if these coils have resistor wires or not. Even if you don't have a radio, they can put out enough noise to false trigger an inductive timing light or make a digital voltmeter read goofy.

Bike has new set of points/condenser from Z1E, maybe only a few hundred miles on them.

At slow speeds and low RPM's it seems a little rough. 20mph and under 2k its a little jerky. Under load its fine. But that place where the throttle is just barely cracked open the tiniest amount seems to be nasty,

The bike seems to pull hard at WOT, but I honestly have no reference to if it has full power or not. I've never ridden another Kz1000 so I have no idea how mine compares.

The carbs are clean, all stock intake airbox/exhaust setup, stock jets, new stock type air filter, valve clearances set, new carb holders and airbox tubes. Yes, I am sure the carbs are clean, spotless, float level set w/clear tube and getting good voltage to the coils. The only thing I have not done is to vacuum synch the carbs, I just did a bench synch.

I believe my symptoms could be the carbs needing synch....its at that tiny bit of throttle opening position where the bike seems to not be 100% right. It's not like it tries to die, just a little rough and sometimes a tiny little cough at idle. At higher speeds that require a bit more throttle opening it runs great.

But just wondering if I should change my coils too because the spark does look weak to me.

Was any gasoline whatever admitted to the freshly cleaned carbs without having first passed through a good in-line fuel filter?

Running sync is necessary to smooth idle and low rpm performance. The pilot screws are also adjusted incident to the running sync.

Of course, a weak spark isn't contributing to good performance. Whether new coils would further improve low rpm performance after syncing the carbs is anybody's guess. But would first sync the carbs, because that's definitely needed, and might go a long way toward improving the idle and low rpm performance, even with the existing coils.

Would put new coils and new Dyna solid copper core plug wires on the to-do list. After installing new coils and wires, most folks regret not having done so much sooner.

Good Fortune!

74ullc wrote: Bike has new set of points/condenser from Z1E, maybe only a few hundred miles on them.

At slow speeds and low RPM's it seems a little rough. 20mph and under 2k its a little jerky. Under load its fine. But that place where the throttle is just barely cracked open the tiniest amount seems to be nasty,

The bike seems to pull hard at WOT, but I honestly have no reference to if it has full power or not. I've never ridden another Kz1000 so I have no idea how mine compares.

The carbs are clean, all stock intake airbox/exhaust setup, stock jets, new stock type air filter, valve clearances set, new carb holders and airbox tubes. Yes, I am sure the carbs are clean, spotless, float level set w/clear tube and getting good voltage to the coils. The only thing I have not done is to vacuum synch the carbs, I just did a bench synch.

I believe my symptoms could be the carbs needing synch....its at that tiny bit of throttle opening position where the bike seems to not be 100% right. It's not like it tries to die, just a little rough and sometimes a tiny little cough at idle. At higher speeds that require a bit more throttle opening it runs great.

But just wondering if I should change my coils too because the spark does look weak to me.

Sounds more like carbs.

Yup, gotta vacuum sync the carbs before I go any further. Thats probably what it is.

I still don't think it would hurt to get some fresh coils/wires in it. I know where a set of vacuum gauges is, just gotta get over there to use them.

Doubt you will gain anything by replacing the coils. The "fat blue spark" concept is a misnomer. If you can see a spark during daytime lighting conditions that should be fine. Check in a dark room and that spark will look brighter and bluer.

I suggest you check voltage at the coils to make sure there isn't any resistance issues leading to voltage loss. Anything less than 11 volts indicates some maintenance is needed. Plug caps sometimes go bad so you might want to check resistance, and/or the connection between the cap and the wire. Unscrewing the cap and snipping off a small section of high tension lead, before reinstalling the cap sometimes helps renew the connection too.

Bottom line, get some measurements and do some maintenance before just randomly changing the coils. The problem described sounds more like carbs anyway (as the others have suggested).

Good luck.