(K)Z200 Electrical/Battery Question

Hi All,

I have a 1979 Z200 (non CDI) that I've been playing with (new to bike electrical systems!). It was sat for a long time, but I have got it running. I had a problem where the bike would tick over fine, but would bog down and eventually die when the RPM was more that 3000. I was convinced that it was a carb issue, but soon discovered that it wasn't. I fitted a new battery and found that all the problems disappeared. The question is, why won't the bike run without a battery? I would have thought the rectifier/regulator could supply the required voltage/current? I've checked the voltage for the reg/rec and it's good at 13.5V. Without the battery fitted, the voltage on the battery cables is all over the place and quite high (both AC and DC). If I fit the battery, the voltage across the battery is steady and being charged as you would expect. Am I missing something and is it possible I have another problem, possibly with the condenser?

Thanks in advance.

I think the battery kind of acts as a large capacitor. Also, the battery is part of the working ignition system >> it probably says so right there in the service manual.

It looks to me like you answered your own question. Without the battery in place, the regulator thinks the battery is completely discharged and is throwing everything it can at the missing battery to charge it. There will not be enough left over to power the ignition, especially under load.
By the way, almost all KAwasaki bikes are non-CDI. Kawasaki tried CDI on the three cylinder two stroke bikes for a couple of years, and gave up on it. The electronic ignition used on later KZ bikes is Kettering, not CDI.

Thank you for the reply.

Yes, to be fair it does say in the manual that the battery is needed to run the ignition system.

How do some people remove/delete the battery on Cafe Racer builds, for instance?

I believe some guys install a large capacitor. loudhvx probably knows what they use. His bare bones for mattylight topic probably has several wiring diagrams for going battery-less.

Do not run the bike without a battery in place as that may cause damage.

Regarding the bike not running well with a bad battery - I don't know what charging system your bike has, but if it is an "excited field" system similar to that on my 1977 KZ650 it must have a decent battery or the bike either will not run at all or will run extremely poorly depending on how weak the battery is. Ed

Thank you.

After reading your reply, it's making me think that maybe a capacitor will solve the problem.

Apologies, I don't know much about bikes in general.

Some of the cafe bikes are running really small lithium iron batteries that can easily be hidden.

To go completely battery less will require a special capacitor or some other electrical wizardry. Perhaps Lou or Bountyhunter or one of the others electrical geniuses will be along to provide a better explanation.

You guys have it pretty much on the head.

The battery smooths out the pulses from the alternator. Like Martin said, without it, you will need a capacitor to do the smoothing. Without it, the regulator can't regulate properly.

Like Texas said, the regulator is struggling to raise the voltage, but without the battery or capacitor, the voltage fluctuates wildly from being too low to too high and the regulator is not fast enough to control it.

Like Ed said, this fluctuation can lead to very high voltage on the bike components and can lead to damage. People have melted light bulbs due to a battery becoming disconnected.

Excellent, thank you.

I blew all the bulbs in about 2 minutes when I was testing it!

Do you have any experience with capacitors and specifying the correct one for the application?

My bike is very rough (recently acquired it for free) so I’m thinking of riding it for the summer to make sure it’s ok then potentially turning it into a tracker or similar.

If yours is like that of the U.S., then it probably uses a 1-phase permanent magnet alternator. That means the alternator and reg/rec have 2 yellow wires connecting them.

If that's the case, then you probably want to find a 5000 to 10,000 micro-farad (aka uF) capacitor. It should be electrolytic type and have a voltage rating of about 50V to 100V. I would find one with screw terminals for convenience. It will have markings for + and - and you hook it up just like a battery.

If your reg/rec has a brown wire, you will want to alter the wiring so the brown wire connects directly to the output wire of the reg/rec. The output wire is usually red or white or red with white stripe or vice versa.

You will also need a switch of some sort to make sure you can shut off all the lights while starting. When lights are turned off, they act like a short until they heat up and start producing light, so they can prevent startup without a battery. Once the bike is started, you give it a little rev and turn the lights on.

But you will want to make sure the bike starts easily with one kick before modifying it all. You said it was starting already without battery so it's probably ok.

Awesome info. Thank you very much.

Yes, that’s the one. Two yellow wires in to the RR. I will look for said capacitor and give it a go. The bike is starting either first or second kick.

Thanks again!