TOPIC:

after about a 30 min cooldown, bike would restart and go about 1.5 miles then quit again. Carbs and peacock freshly rebuilt. Will know if gas flows after tow home. 1980 kz650 Ltd. Any thoughts appreciated

Was it a sudden shutdown or did it sputter?
Was it hot outside?
When you tried to restart, did it seem like it wanted to fire?
How much gas is left in the tank? Is it near the reserve point?
Did all of your electrics still work when it shut down?

Tank was full. Did not sputter when I tried to immediately restart, but fired immediately after cooling for 20-30 mins and idled fine. Have to be honest and say I did not notice if headlight was still on. Turn signals were kind of slow on the ride. A buddy thinks its the stator. How can I test that to know one way or another? Bike does have a tendency to kill batteries over the riding season. Maybe a regulator issue?

Is it stock ignition?

The best way to keep an eye on charging issues nowadays is to just mount a small voltmeter somewhere and have it connected to the battery. They can be had pretty cheap and are small enough to hide somewhere.

When actually riding, the voltage should be somewhere between 14.0 and 14.5v.

rebreath wrote: Tank was full. Did not sputter when I tried to immediately restart, but fired immediately after cooling for 20-30 mins and idled fine. Have to be honest and say I did not notice if headlight was still on. Turn signals were kind of slow on the ride. A buddy thinks its the stator. How can I test that to know one way or another? Bike does have a tendency to kill batteries over the riding season. Maybe a regulator issue?

Testing the charging system is pretty simple, but you need to follow the instructions in the Kawasaki Service Manual. Keep in mind that Kawasaki used a variety of different charging systems on the different year KZ650 models, so be sure to find a manual that covers your bike's exact year and model. Ed

rebreath wrote: A buddy thinks its the stator. How can I test that to know one way or another? Bike does have a tendency to kill batteries over the riding season. Maybe a regulator issue?

If you started it up 30 minutes later, then it's probably not the charging system. It's certainly not under-charging. If it's overcharging that will kill the batteries like you said, but it usually won't temporarily stop the ignition, it will usually just kill it alltogether.

But first thing to check is the charging voltage. Check it at idle, then at cruising rpm, and then repeat the process with the headlights on. The headlights could drop the voltage if the charging system is weak, but it normally raises the voltage a little. Many of these bikes take their regulator sense wire from the accessories, so when the headlights are on and the accessories circuit voltage drops, the regulator increases the charge voltage to compensate, and since the accessories has a lower voltage, starts overcharging. If it's charging over 14.5 at any time, it's overcharging. I'm not sure if this is the same on the 650's, but if you're overcharging and it gets worse with your headlights on, that's probably it.

Having said all this, while it could be electrical (some bad coils also become intermittent when hot), it might not be. If your tank cap isn't venting correctly, it can cause a vacuum after riding for a while. If the bike dies, open the cap - if you hear air rushing in after opening the cap, and the bike runs again, then it's the cap.

Could this also include undercharging? By killing batteries i mean that over the course of the season the battery got weaker and weaker. By the end of fall battery was nearly dead. Undercharging could represent by a dim headlight at idle and brighter at higher rpms couldnt it?? The turn signals were blinking pretty slow even at higher rpm. Also, wouldnt a failing charging system drain the battery, killing spark and causing shutdown. Wouldnt the battery generate some charge on its own thru normal process and thus allow starting and running until it drained again? I will test tomorrow and see what I find. I did not put it on the charger cause I want to see voltage of battery in the am. I will post what I find. Thank you to all that made suggestions and shared insights. Hadnt considered the tank cap..will have to check that as well.

If you started it up 30 minutes later, then it's probably not the charging system. It's certainly not under-charging. If it's overcharging that will kill the batteries like you said, but it usually won't temporarily stop the ignition, it will usually just kill it alltogether.

But first thing to check is the charging voltage. Check it at idle, then at cruising rpm, and then repeat the process with the headlights on. The headlights could drop the voltage if the charging system is weak, but it normally raises the voltage a little. Many of these bikes take their regulator sense wire from the accessories, so when the headlights are on and the accessories circuit voltage drops, the regulator increases the charge voltage to compensate, and since the accessories has a lower voltage, starts overcharging. If it's charging over 14.5 at any time, it's overcharging. I'm not sure if this is the same on the 650's, but if you're overcharging and it gets worse with your headlights on, that's probably it.

Having said all this, while it could be electrical (some bad coils also become intermittent when hot), it might not be. If your tank cap isn't venting correctly, it can cause a vacuum after riding for a while. If the bike dies, open the cap - if you hear air rushing in after opening the cap, and the bike runs again, then it's the cap.[/quote]

rebreath wrote: Could this also include undercharging? By killing batteries i mean that over the course of the season the battery got weaker and weaker. By the end of fall battery was nearly dead. Undercharging could represent by a dim headlight at idle and brighter at higher rpms couldnt it?? The turn signals were blinking pretty slow even at higher rpm. Also, wouldnt a failing charging system drain the battery, killing spark and causing shutdown.

Yes, this is all correct.

rebreath wrote: Wouldnt the battery generate some charge on its own thru normal process and thus allow starting and running until it drained again?

No. A bike requires very little current to continue running, maybe an amp or two with some basic accessories. But starting a bike is the biggest single load you would put on the battery, typically 50-150 amps depending on your engine size. If the battery has been drained to the point where it can't provide the little amount required to keep the engine running, then it will not have the power to start the bike again with recharging it first.

Even a dead battery can usually keep a bike running once it's started, since the bike's charging system can provide the power to keep it running. That's why you can often jump-start an engine even if it has a completely dead battery.

What this means is that if your engine dies, but you can start it up again later without charging the battery in between, it didn't die from the battery undercharging. If it dies from undercharging, it will not start again unless you jump-start it, or the battery is charged.

How any miles since the last valve adjustment? Poor running when hot is a common symptom for tight valves.

In actual ridden miles maybe 200 miles ago. Bike hasn't been on the road tho since 07. Thats when my first was born. Changed my riding schedule severely..lol

makes perfect sense..looks like i got some sleuthing to do

I helped someone years ago that had the charging system issue. It would die then he could restart it after the battery recovered, but it would run for less and less each time.
Anyway, find your meter.
Set your meter for DC V.
Black meter probe on the neg battery post(the metal part of the battery not the connector for the battery cable)
Red meter probe on the positive battery post
Note voltage

Fire up the bike
Note voltage
Raise to 3000rpm
Note voltage
Raise to 5000rpm
Note voltage

Let idle
Turn on high beam and one turn signal
Note voltage
Raise to 3000 rpm
Note voltage
Raise to 5000rpm
Note voltage

Turn off bike

Your readings should stay above 12.6.
At idle the bikes usually don't charge. You have to bring the rpm up a bit to get the charging hence the 3000,5000rpm. If the battery is overcharging, the voltage will climb well above 14 with the higher rpms.

You turn on the high beam and turn signal to see if the charging system can handle a bigger load and maintain the 12.6v to 14.4v.
Ok, let us know what you find.