Wrong Capacitor or Dyna S?

So, a while ago I bought a capacitor because I would like to goto a battery-less bike. I love kickstarting the thing.

Anyways, after some research on capacitors and what not, I bought a 5,600uF 75VDC (the u is the greek mu for mico) capacitor.

I finally got to hooking it up to my bike instead of the battery and it starts on the first kick after being cold. Yay!

But if I turn on the lights while it's idling, the bike dies (now I have TWO kill switches *grin*).

I can turn on the lights when I have the engine reved, and it will even idle after that, but the head light and tail light are VERY dim.

My question is: Did I buy the wrong capacitor? Or does my Dyna S draw too much power for a capacitor. Any thoughts would be appreciated.

I can turn on the lights when I have the engine reved, and it will even idle
after that, but the head light and tail light are VERY dim.

When it's idling and you turn on the lighting the cold resistance of the
filaments is very low and puts a huge momentary load on the system. When
you rev it up and turn on the lights, there is enough power to keep
everything going. Now when you let it drop back to idle, the filaments are
'lit' so you don't get the surge. A larger capacitor may help but...

No matter how large a capacitor you have, the lights are not going to be any
brighter at idle. The mag just isn't spinning fast enough to make any more juice.

I suggest you call dyna and ask to speak with an engineer. Explain what's happening
and ask him if he has any suggestions. I can think of a bunch of things to try but
they all shots in the dark without knowing how the thing is designed.

-Duck

Your Dyna ignition uses twice the power of the stock unit. If you go to a stock Kawasaki electronic ignition, you will cut your wasted ignition power by more than half. That will give you an extra 30 to 50 watts or so at idle.

There is no easy way to make the Dyna more efficient. It wastes a lot of power at idle.

I just don't think the Dyna is a good match for going batteryless.


Also, since your bike is a single phase charging system, a bigger capacitor would probably help.

It would be easier to suggest solutions if could provide more data. What is the voltage on the capacitor at idle with the lights off?

When you rev it, what is the voltage at 3000 rpm with lights on and with lights off?

I can get that info. Will probably be later in the week though. I'll post it as soon as I have it.

The only thing I'm scared about going to a bigger capacitor is charge up time. If I can't do it in one kick, then it's no fun. *grin*

I could show you a simple circuit that uses a standard 9v battery to charge the capacitor so it will have 9 volts on it before you even try to kick.

It requires a little bit of rewiring to make sure everything is off before you try to kick. It won't work with a Dyna or points though... only for the stock electronic ignition (which is a bolt-on) from early 80's 550's and 650's.

Rstnick is using one from a 1000, but he had to do some modification to the timing plate.

You really just need the pickup/timing plate. You can make the module yourself for about $30.

That said, even points will only use half the power the Dyna uses. You could try an experiment and go back to points if you still have them. If it idles with lights on using points, then you know it will work with stock electronic ignition.

I used both a 5600 uF and a 12000 uF and found both just as easy to start, but I was using bumpstart on my 550 (no kick option). It started immediately with lights on and had about 13 volts at idle. It is 3-phase though.

You may also think about ebaying a 3-phase stator from an 81 or 82 650H (csr) if you can find one cheap. I'll check Kawasaki to see if they share the same flywheel. EDIT: I just checked, the flywheel has a different number.


I know Stef could run his 400 batteryless with lights on and he has a single phase stator. He was running points.

Post edited by: loudhvx, at: 2006/04/16 09:53

Post edited by: loudhvx, at: 2006/04/16 09:55

I think I'll take the readings and see what they say. There is further complications about my electrical system. Mainly, I have 3 tail lights in the back, as my turn signals are dual filament and red, so I leave them on when the lights are on and they blink brighter to turn (just like the front).

So if the voltage is too low, maybe first I could switch out those incandecent bulbs to LEDs. That should significantly lower the running voltage on the bike if I do all three tail lights and the front turn signals.

All three tail lights combined probably are less than 1.5 amps at 12 volts.

The Dyna ignition is using 7 or 8 amps at 12 volts (with 3-ohm coils).

Points would use about 3.5 to 4 amps at 12 volts (with the same 3-ohm coils).

The stock electronic ignition would use about 2.3 to 2.6 amps at 12 volts (with the same 3-ohm coils).

A 55 watt headlight uses about 3.5 amps at 12 volts (it doesn't produce 55 watts at 12 volts, it's usually rated at 14 volts).

We know your headlight makes the difference. So we know sparing 3 or 4 amps will do the job.
Will 1.5 amps make much difference? Hard to say, but I think you may need to save a few more amps than that. It'll be a good experiment though. Just pull out the three bulbs and see what happens.

I don't doubt the 8-9 Amps for the Dyna. I'm just trying to imagine where the extra(over stock) 70W or so is going, and why.

The Dyna is using an extra 50 watts or so.

loudhvx wrote:

The Dyna is using an extra 50 watts or so.

But what is it using it for?



Dyna has installation guides on their web site. Man they have a bunch of different models.


Here is some dyna and boyer info with testing and installation tips.

Post edited by: Duck, at: 2006/04/17 17:11

Duck wrote:

loudhvx wrote:

The Dyna is using an extra 50 watts or so.

But what is it using it for?

The Dyna uses a static-dwell ANGLE. Due to its design (Hall-effect with magnet-rotor), the dwell is nearly 360 degrees of crank rotation. In comparison, the points are 180 degrees.

This gives better dwell-TIME characteristics at higher RPM. This means more spark energy at higher RPM. However, the down side is a lot of wasted energy at idle. The wasted energy is converted to heat inside the spark-coil. It is not a desired feature, but is a side-affect of having a large, static dwell-angle. The extra dwell time at idle is not converted to spark energy because the coil is saturated within the first few milliseconds. After that, all you get is more heat in the coil.

The Kawasaki electronic ignition varies the dwell-angle from about 100 degrees to 120 degrees. This is very good for conserving electricity at idle. Optimally, the Kaw ignition should use 2.4 ohm coils, but it works fine with 3 ohm coils.

If a change in spark energy produces a noticeable change in engine power, then the jetting is probably off. It has been shown that spark energy should not affect a properly jetted, stock motor much at all.