Kz650 won't run for more than 15 minutes in town

Hi everyone, this is my first time posting but I wanted to preface this post by saying thank you to everybody that has contributed do this form because it does help immensely with my project bike.I own a 1981 Kawasaki KZ650 CSR H1 and have loved every minute of the restoration and customization process. But recently my bike has been having some issues with how it runs.The engine will start up almost immediately just fine and after warming up, it will run fine, albeit with a bit of a hammering noise between 3000-5000 rpm under load (which I am also trying to chase down and fix). The issue however occurs when I run the bike for about 15 minutes around town, it seems to lose charge and dies, stranding me at the gym/store/etc.Now I have a few modifications to the electrics on this bike including swapping over to all LEDs and 1157 bulbs, having a running light as well as a night light and high beam (makes night rides much more comfortable for me), and likely the most important modification and where I believe this issue is stemming from: a dyna S DS2-2 ignition timing system with 3 ohm coils. I’ve read that this has been an issue with many KZ riders as it drains the batter due to a longer dwell time. However I only read about this occurring with single phase generators and I am certain mine is 3 phase. It also produces 50V A/C at all 3 test points but does have an impedance above recommended of 1.4 ohms. I have ordered a new stator to rectify this issue and I have also tested my R/R which is also up to par.I guess what I am looking for is to make sure that I am not missing anything obvious or if it could be anything else that I could check in the meantime.Thanks in advance, Marc

grab your meter
DC V

key switch off
kill switch off

red probe on positive battery post(post being the metal part of the battery)
black probe on negative battery post
what is your voltage to the tenth(ex 12.3v)

key switch on
what is your voltage to the tenth?

start the bike
let it idle
what is your voltage?

turn on your high beam
what is your voltage?

raise your rpm to 4000
what is your voltage?
 
let the bike idle
move your red probe to a metal part of the engine case.
what is your voltage? (it should be a steady 0.0volts. any higher than 0.5v then you have a bad engine ground. If the voltage fluctuates then you have ghost voltage, which means your ground is disconnected)

turn off bike.

After charging the battery, the voltages are as follows:

key switch off/kill switch off : 12.6 V
Key on: 12.5
On idle its at 12.6
At 4000 rpm: 13.1
Engine ground is steady at 0 volts

forgot to check the highbeam but I doubt it's the cause.

I took the bike around my neighbourhood to replicate the problem and when the bike dies the voltage of the battery is 11.8, again suggesting an issue with the charging system.

The high beam on is just to put a higher load on the charging system. I want to see if the charging system can keep up.
You may have to hook up the meter to your bike when riding.. not the safest thing.
Something may be failing due to heat, vibration, or just being weird while you are riding.

Ah okay I gotcha, I can definitely give that a go today after work. I wouldn't be surprised if heat is killing something in the charging system. I'll set up some aligators and put the meter by my tank while I ride to keep an eye on it. Thanks for the advice.

I had a similar issue with my 77 KZ650.  It finally came down to dirty corroded connections leading to the fuse box.  I suggest cleaning with very fine emery cloth and/or electrical connection cleaning spray.  I recommend the spray.  Once I used it.  I had immediate ignition and bike runs great without issues.  This of course is a solution if you do not really have a charging issue.  I would start with cleaning connections before tearing into and trying to track down other wiring and charging issues.  

Here is a link for the contact cleaner.  You can get at Guitar Center, Amazon, etc.  >>>>   CAIG DeoxIT D5S-6 Spray, Contact Cleaner / Rejuvenator, 5 oz. | Guitar Center

I can certainly give that a go, however I don't believe that's the cause. The symptoms I'm having are that the bike starts up cold no problem. Then I ride and the battery drains where it then stops. If I try and start the bike up again, the starter motor struggles. If I short the connection between the solenoid, the same thing occurs and continues to do so until the bike is cold.

I'll give it a shot anyway because I'd rather eat my words and ride than not.

wrote:

After charging the battery, the voltages are as follows:

key switch off/kill switch off : 12.6 V
Key on: 12.5
On idle its at 12.6
At 4000 rpm: 13.1
Engine ground is steady at 0 volts


 

These voltages should not be draining your battery. 12.6 at idle indicates charging output is just keeping up with the load. No charging but no draining either.
13.1v at 4k is charging at a trickle charge rate,
Monitor your voltage while riding. Something is dropping out for a fully charged battery to die that quick.

Pull the battery. Charge it. Then take the fully charged battery to your local auto parts store and have them load test it. Diagnosing is a process of testing and eliminating good parts till you find the bad one.

I load test batteries using a 60W head light bulb.
60W at 12V draws 5 amps, So a New, fully charged, 10AH battery should last 2 hours. If I get at least 50% of that burn time, I consider the battery good.

wrote:

I can certainly give that a go, however I don't believe that's the cause. The symptoms I'm having are that the bike starts up cold no problem. Then I ride and the battery drains where it then stops. If I try and start the bike up again, the starter motor struggles. If I short the connection between the solenoid, the same thing occurs and continues to do so until the bike is cold.

I'll give it a shot anyway because I'd rather eat my words and ride than not.

Are you saying that the bike starts ok after it has cooled down without re-charging the battery or using jumper cables ? - If so this is not a charging issue, a battery simply stores electrical energy so once you have used it you need to replace that used energy (re-charge it) unless there is some "alchemy" afoot a battery won't re-charge itself.
Once the bike is running the electrical system runs from the generator and the excess is used to top up the battery (if your battery was flat and you bump started the bike by rolling it down a hill it would continue to run), therefore unless the battery is totally "goosed" it won't cause the bike to stop once running and it certainly wouldn't be able to re-start under it's own steam. I am with Forrest on this one, I believe your issue is corroded electrical connections causing a resistance.
The reason I think this is simply, when you have a corroded connection it causes resistance - a by-product of resistance is heat build up - heat causes an increase in resistance - which in turn generates more heat - this cycle continues until the resistance is so great that not enough current can flow for the bike to work. When it dies and you turn it off there is no current flow so the resistance (corroded connections) cools down and again allows current to flow and the bike to re-start. At this point the whole process of heat build up starts all over again.
This is the most common cause of the type of fault you are describing (breaks down every 15 minutes - re-starts after a short while.

Just out of interest have you checked that it's not a mechanical issue causing the motor to tighten up when hot ??

 

Weak coils overheating in town traffic due to no airflow to cool them.