Weak spark/ Iridium plugs dead

[fastdougzrx]

Long story but I'll try to keep it short. Bike has been running great all year until yesterday. Got home from work after daily 35 mile commute parked bike for a few minutes then went back out but bike was running like crap, almost like it was starving for fuel but still had half a tank. Went back home and let bike cool down completely. Started it back up and checked pipes. 2&3 felt like they weren't warming up as fast as 1&4. Pulled seat and tank to check plugs. Plugs looked ok, they are iridiums that I put in last spring, about 6k miles ago. Checked spark and it was barely visible on all four. My first thought was coils or ignition. Luckily I still had the old stock type plugs from last year. Cleaned them up put them on to check spark and spark was huge. Put them in, put bike together and took it for a test ride. No problems. Started back up good when hot.

This morning bike started a little hard but that's why I had replaced those old plugs to begin with last year. Once started it ran great all the way to work.

Any thought? Can iridiums just die like that. The day before the failed plugs, the temp here was near 100 and I rode the bike (again 35 miles each way) but it seemed to handle it ok.

[Cadman]

Spark color can tell you something about the voltage.
A fat yellow/orange spark won't jump too far because it's low voltage.
A thin blue/white spark is a normal high voltage one. If you see a thin blue spark that won't jump very far, then it's got resistance elsewhere before it gets to where you are checking it.

The coil will only produce enough voltage to go to ground. The farther it has to jump, the higher the voltage.
Fresh plugs will take less voltage to fire and can cover up a low voltage issue. If it will run well at full throttle and high RPM then your coils and ignition circuit are fine. If both coils have issues, then look for what they have in common as they are very unlikely to fail at the same moment. The primary (small wires) connections can come loose and that could make them temperature sensitive as they expand when heated. As they are two seperate wires, I would look where they come from to find what they have in common. I am at work and do not have a manual here to look that up.
Do I think that 4 plugs picked the same moment to fail? No. Possibly you disturbed the connection issue while changing the plugs.
I would separate and use contact cleaner on the harness plugs that are related to the supply of power to the ignition circuit.

[skandix]

I had one IR go bad that way due to running rich last year. How did the plugs look?

[fastdougzrx]

Spark color can tell you something about the voltage.
A fat yellow/orange spark won't jump too far because it's low voltage.
A thin blue/white spark is a normal high voltage one. If you see a thin blue spark that won't jump very far, then it's got resistance elsewhere before it gets to where you are checking it.

The coil will only produce enough voltage to go to ground. The farther it has to jump, the higher the voltage.
Fresh plugs will take less voltage to fire and can cover up a low voltage issue. If it will run well at full throttle and high RPM then your coils and ignition circuit are fine. If both coils have issues, then look for what they have in common as they are very unlikely to fail at the same moment. The primary (small wires) connections can come loose and that could make them temperature sensitive as they expand when heated. As they are two seperate wires, I would look where they come from to find what they have in common. I am at work and do not have a manual here to look that up.
Do I think that 4 plugs picked the same moment to fail? No. Possibly you disturbed the connection issue while changing the plugs.
I would separate and use contact cleaner on the harness plugs that are related to the supply of power to the ignition circuit.

Iridiums had a thin/blue, barely visible spark. Used stock style plugs from last year had a fat orange spark which I assumed was better. Bike started a little hard when cold this morning. Same thing when I started it to come home from work today. Stopped at a gas station and it restarted ok. Stopped at a local shop to buy new stock type plugs, came back out and bike cranked but no fire. Had to change the plugs right there in the parking lot. After that it fired right up. No time to check the spark on the new plugs tonight so I'll see how it starts in the morning. I appreciate the advice Cadman, thanks.

[fastdougzrx]

I had one IR go bad that way due to running rich last year. How did the plugs look?

Plugs looked a good, I think. Kind of a greyish color.

[fastdougzrx]

I had one IR go bad that way due to running rich last year. How did the plugs look?

Btw, I like the paint job.

[skandix]

Btw, I like the paint job.

Thanks, how old is your battery? LIke Cadman said check and clean your wires and plug wires.

[Cadman]

I was just making dinner and flashed on the battery. Skandix is right.
When the battery is going out, or low on water, it will crank at what seems to be a good enough rate, yet it won't fire.
The only time my bike has not started, that was the case.
My GPz does that because it sits so much. If it doesn't fire right away, I just jump it and it lights right off.
The starter draws down the voltage on a weak battery to the point where there is not enough power to provide a quality spark.
Sorry I did not think of it sooner.

[fastdougzrx]

Thanks, how old is your battery? LIke Cadman said check and clean your wires and plug wires.

Battery is ancient. I've had the bike since 2001 and don't remember changing it. I'm thinking there's no way this is the original battery, never heard of a bike battery lasting that long. Although I don't remember doing it, I must have replaced it once but it would have been a while ago. Time for a new one, huh?

[Cadman]

Maybe. Some guys have gotten a lot of use out of their batteries. It doen't cost anything to take a look at the water level. Distilled water is best and don't over fill it. I use a little squeeze bulp so I can control the filling. Battery acid will mess up metal, stain the floor, and ruin your clothes.
When mine did not start up, I was 500 miles from home and it was cold and drizzling. I rolled it down a hill and it lit off and was good the rest of the day through multiple starts. Just like the GPz, it seemed like it was cranking fast enough. When I got home I pulled it out and it was low on water. I filled it and charged it. It worked ok, but I didn't trust it now, so I bought a new one and gave the old one to a guy who needed it.
I have to put water in the GPz every 6 months. That is a sign of over charging, but a regulator swap has not changed its need for maintenance. High cruise RPM may play a part in that.

[sillyhillbilly]

Battery is ancient. I've had the bike since 2001 and don't remember changing it. I'm thinking there's no way this is the original battery, never heard of a bike battery lasting that long. Although I don't remember doing it, I must have replaced it once but it would have been a while ago. Time for a new one, huh?

yep time for a knew one
at 11.8 vdc the battery wont power the cdi, and thus the cdi wont fire the coils, thus no spark, you think its fast enough on starter speed, but the drop in voltage cause failure of ign system
i bet you can take said battery to parts store for a load test, if it drops below 12 vdc its history

[KWICK]

Also, be sure the sparkplug caps have NO oil on them, and that they are pressed ALL the way into the head and that you can feel the 7 or 8 threads on the plug clicking.

A leaky valvecover gasket set gets oil on them and grounds them.
The caps not seated cause a spark leak to the plug hex.

[fastdougzrx]

Also, be sure the sparkplug caps have NO oil on them, and that they are pressed ALL the way into the head and that you can feel the 7 or 8 threads on the plug clicking.

A leaky valvecover gasket set gets oil on them and grounds them.
The caps not seated cause a spark leak to the plug hex.

Funny you should mention oil. When I first pulled out #1, when I grabbed it out of the socket wrench I got oil on my fingers. I was freaking, thought I blew it up. On close inspection, the oil was only on maybe 4-5 of the plug threads closest to the hex. Tip looked good, so did ceramic, plug cap and no oil that I could feel in the head where the plugs go... #4 was the same way, little bit of oil around the upper most threads. Compression felt good on all 4 but I didn't measure it and no oil pumped out when I cranked it over. Tops of all 4 pistons looked good. Perhaps valve cover seap but I didn't see it.

[KWICK]

Funny you should mention oil. When I first pulled out #1, when I grabbed it out of the socket wrench I got oil on my fingers. I was freaking, thought I blew it up. On close inspection, the oil was only on maybe 4-5 of the plug threads closest to the hex. Tip looked good, so did ceramic, plug cap and no oil that I could feel in the head where the plugs go... #4 was the same way, little bit of oil around the upper most threads. Compression felt good on all 4 but I didn't measure it and no oil pumped out when I cranked it over. Tops of all 4 pistons looked good. Perhaps valve cover seap but I didn't see it.

If there's oil on your plug boot and plugs, the only way it can get there is thru the valvecover gasket set.

[fastdougzrx]

If there's oil on your plug boot and plugs, the only way it can get there is thru the valvecover gasket set.

Thanks Kwick. When I first saw the oil on the top threads of 1&4, I was thinking something catastrophic to allow oil into the cylinder (rings, valves or valve guide seal). But if I have a valve cover seap, it makes sense that the oil would settle around the base of the hex and run down the threads as I remove the plugs. Time for a valve adjustment soon so I'll have to check that gasket when I'm in there.

[KWICK]

Thanks Kwick. When I first saw the oil on the top threads of 1&4, I was thinking something catastrophic to allow oil into the cylinder (rings, valves or valve guide seal). But if I have a valve cover seap, it makes sense that the oil would settle around the base of the hex and run down the threads as I remove the plugs. Time for a valve adjustment soon so I'll have to check that gasket when I'm in there.

Again, it is the gasket set, you'll need to replace the set.

[fastdougzrx]

Again, it is the gasket set, you'll need to replace the set.

Gotcha. If I remember right, it's one main one around the outside and four smaller ones around the spark plug openings. Either way, I'll remember set. Thanks man!

[KWICK]

Gotcha. If I remember right, it's one main one around the outside and four smaller ones around the spark plug openings. Either way, I'll remember set. Thanks man!

And the six seals under the bolts

[fastdougzrx]

yep time for a knew one
at 11.8 vdc the battery wont power the cdi, and thus the cdi wont fire the coils, thus no spark, you think its fast enough on starter speed, but the drop in voltage cause failure of ign system
i bet you can take said battery to parts store for a load test, if it drops below 12 vdc its history

2nd day now with new plugs and bike is running great. Got to thinking about the weak battery/ weak spark/ won't start scenario. The first symptom I had with the iridiums was poor performance, not won't start. Bike started but ran like crap. If the battery was low to give me weak spark, that shouldn't effect performance once the bike was running, right? (charging system compensate for low battery)

[Cadman]

Sort of. Bikes have to be reved some to charge. If you have been riding for a few minutes (above 4000 rpm) and roll on the gas, and it starts dropping cylinders, then that is not likely to be the battery. The reason it would run badly with one kind of plug and not another would come back to the voltage required to fire the plug excedes what the coil can deliver at that moment or it is jumping a gap to ground before it gets to the plug gap.
Example: new plugs are gapped at .050 when the gap should be much smaller. Plug does not connect in boot causing an additional gap to be jumped. Your friend plays a little joke on you by putting a pencil line on the insulator. Heat range of plug is way out of line and detonation applys a coating of melted metal on the insulator (high speed glazing). Your moon and stars were out of alignment that day.

Glad the bike runs good now. I have rolled a bike down a hill to start it and the battery was so dead it would not idle and I had to start it again and keep it reved up. It ran fine and the battery charged up enough in a mile or so where it would idle ok too.

[sillyhillbilly]

2nd day now with new plugs and bike is running great. Got to thinking about the weak battery/ weak spark/ won't start scenario. The first symptom I had with the iridiums was poor performance, not won't start. Bike started but ran like crap. If the battery was low to give me weak spark, that shouldn't effect performance once the bike was running, right? (charging system compensate for low battery)

no. not always, bike wont runn if you remove the battery after starting, same thing with dead battery, if it craps out completely while motor is running it can die and your stranded, same deal as trying to push start on dead battery, wont happen, while it might run some. first or second or third stop and rpms drop, then its dead and wont restart

[KWICK]

The ZRX alternator has a field coil that needs to have voltage of 12V or so in order for the alternator to charge properly.

If you spin the ZRX alternator to 10,000 rpm without the field coil charged it'll put out 1.8 volts....really.

[Cadman]

We are all in agreement. He said his battery was old, but it WOULD start. It ran badly with plug A and good with plug B. We all agree that a battery that is dead dead will not keep the engine running. I have not push started a bike with a dead dead battery. It would crank, but would not fire the plugs. I have started 2 bikes in that situation by rolling them down a hill and keeping it reved up for a mile or so. The batteries were not defective, just discharged enough to not fire the engine.
True story.

Doug, did you check the water in that old battery? Might need some by now.

[hydrashoks]

no. not always, bike wont runn if you remove the battery after starting, same thing with dead battery, if it craps out completely while motor is running it can die and your stranded, same deal as trying to push start on dead battery, wont happen, while it might run some. first or second or third stop and rpms drop, then its dead and wont restart

well....

ZRX will run w/o a battery.

I've started a ZRX off a jump kit, w/o a battery in it at all, rode it around (in January ), and actually stalled it at a light...I rolled it into second, down a hill, pop started it, and rode it home.

I remember posting this in a thread a few yrs back and got some fun feedback...

[Cadman]

I was afraid this would leak off into that direction............

[hydrashoks]

I was afraid this would leak off into that direction............

[fastdougzrx]

We are all in agreement. He said his battery was old, but it WOULD start. It ran badly with plug A and good with plug B. We all agree that a battery that is dead dead will not keep the engine running. I have not push started a bike with a dead dead battery. It would crank, but would not fire the plugs. I have started 2 bikes in that situation by rolling them down a hill and keeping it reved up for a mile or so. The batteries were not defective, just discharged enough to not fire the engine.
True story.

Doug, did you check the water in that old battery? Might need some by now.

I haven't had a chance to check the water level yet. This weekend for sure. To be honest, I've never checked the water level in a maintenance free battery. Guess I just assumed you don't have to.

I think I forget to mention that on the way home last Thursday, on plug B which were the used plugs from last year, the bike almost left me stranded. Stopped for gas and the bike started right up. Stopped at local bike shop to buy new plugs (got raped, $8.90 each for CR9EK) because I didn't trust the used ones. Came back out and the bike cranked and cranked but no fire. Had to install the new plugs right there in the parking lot. Bike started right up and has been running good since. Need to pull them back out and check gap, didn't have gauges in my tool kit. This has not been my week. I appreciate all the input on here from everyone! Hope I can return the favor some time.

[KWICK]

New NGK's do not need their gaps checked.

[Cadman]

New NGK's do not need their gaps checked.

Pray tell why for? Do their little boxes never get dropped or does the shape of the electrodes render them bullet proof?

[KWICK]

Pray tell why for? Do their little boxes never get dropped or does the shape of the electrodes render them bullet proof?

There are plastic spacers on the plug tips. Unless you step one them and jump up and down and ruin the box, the gap cannot change.

Back in the seventies I was bored at the the Honda dealer...parts was open till 8:30pm... I went thru a couple hundred NGK & ND plugs checking gaps...they were all on the money.

Champions use a weak cardboard box with no spacer. They are often out of whack.