Should engine run on Dynamo when battery is dead?

This morning I attempted to ride my 1978 KZ 200. The battery did not have the juice to start the engine, but kick start fired it right up. The bike was idling quite high. About 1 mile down the road at a stop light, the bike died and couldnt be kick started again. All lights etc. were very dim- battery obviously drained. Battery is on charger now, but wondering shouldnt the engine have been able to run on Dynamo once started? Does it need to be replaced?

A bike like yours can run without the battery under certain conditions. If my memory is correct, your bike has a permanent magnet alternator. This type of alternator can run without the battery in place as long as there is something to smooth out the alternator pulses. A capacitor would make that possible. This type of alternator can also run with a dead battery as long as you can get it started.

However, with what you've described, it sounds like the alternator or regulator/rectifier has a problem.
Do you have a manual?

Here's an online one. It's a little older than your bike, but may be useful.

home.comcast.net/~loudgpz/KawKZ200Man.pdf

I just got to my service manual. As soon as my battery is charged, I'll check the regulator and dynamo output levels.

All theory aside, if it runs at all with a dead battery it will run very poorly at best because so much energy is sucked up by the battery that's there's precious little left for the ignition. If the battery is old just replace it. Ed

Scatnato wrote:

This morning I attempted to ride my 1978 KZ 200. The battery did not have the juice to start the engine, but kick start fired it right up. The bike was idling quite high. About 1 mile down the road at a stop light, the bike died and couldnt be kick started again. All lights etc. were very dim- battery obviously drained. Battery is on charger now, but wondering shouldnt the engine have been able to run on Dynamo once started? Does it need to be replaced?

It's dangerous to run on a bad battery.

The battery acts like a big filter capacitor smoothing out the AC from the alternator. If the battery is hosed, you can get ferocious voltage spikes.

I kick started mine on a bad battery and rode about a half mile and wiped out half the bulbs in the bike along with the electronic ignition module.

Your symptoms sound like your alternator/reg are not charging the battery or the battery is just stone dead.