78 KZ650 B2 Charging/ignition system upgrades

Hello all, mid-project on my first retro/resto...

So I've been trying to piece together information from a handful of KZR threads pertaining to charging systems for the '78 KZ650's... my goal being to get a comprehensive setup retrofitting a Shorai Li battery, and a Dyna S electronic ignition (new coils too).

Here's my train of thought so far: it appears likely the Dyna S could potentially overload the single phase (2-wire stator) charging system of the 650-B2 making it best to convert to a 3-phase system (i.e. new 3-wire stator and a corresponding regulator/rectifier). On that note, (1) it's seemingly difficult to get my hands on a new SH775 R/R so any recommended sources for a SH775? Or if not that, what's the next best option e.g. the FH020? And (2), anyone know of a 3-phase stator that would bolt on, perhaps off a later 650-D4 or H1?

With regards to the battery: It'll be a kickstart-only so is it possible and reasonable to use a 7 AH, 107 CCA battery versus the more expensive 14AH/210CCA? I'm no sparky, so not quite sure what other impacts the lower amp rating may have...

Lastly the ignition coils: safe to say the Dyna 3 Ohm would be the proper selection? However, if I go with a lower amp battery, does that mean I need to up the coil resistance (say to the 5 Ohm) to keep my coil voltage up? Or is it not that simple.

Personally, I'd prefer to plan ahead, confident that everything will be compatible and functional than trying to piece things together individually, test, troubleshoot, etc. trial-and-error style. Then again, part of me's tempted to wing-it and hope the stock single-phase system can keep up.

Thanks in advance for any input!

There is only a chance the Dyna S will use too much power for the single phase system. Some/most of the 78/79 systems are fine with the Dyna S. For some reason, when there is a weakness problem, it appears on the 78/79, but that does not mean all 78/79 are weak. Maybe there was a batch of permanent magnets that were slightly less powerful. If you are not doing a full-rewire, you might wait and see if it works or not, unless money is no object.

If you need a 3-phase system, then I think a 750-four stator should work, as well as the other 650's with permanent magnet 3-phase systems. Others have switched over to ones from 750-fours.

If you are going to kick-only, then you can get away with smaller batteries, regardless of the ignition, as long as the charging system is working well. In fact, once your bike is in really good tune, you could probably get rid of the battery entirely (and use a capacitor) with a factory ignition. (Not sure with the Dyna S, possibly.)

I, personally, would get a sealed AGM scooter battery (from a Honda Spree 50cc) over a lithium. They can handle the imprecise regulation better than lithium, and being so small, they don't weigh much. Also, much cheaper and readily available.

If you are getting full-size Dyna coils, then 3-ohm coils are what you want. (An argument could be made for 5 ohms if you were sticking with points).

If you can't find a series-pass reg/rec, you can always use one from recent a Ninja 250 or 500. They are practically free used.

In either case, don't forget to add the switched 12v wire (usually brown) as that is the sense line for the regulator. The 78/79 650 did not come with that wire.

Exactly the feedback I was looking for. All good recommendations. Thanks!

I will be doing a rewire, and I think I'll plan to go to 3-phase:
- stator fit for an early 80's 750
- 7AH AGM battery (relatively the same dimensions of the Li, although a few pounds heavier; half the cost of the Li; and settles my nerves given some of the negative feedback I've read about Li/Shorai)
- R/R off a late model Ninja 250
- 3 Ohm coils w/ the Dyna S

And great call on the sensing wire. I didn't notice that looking at the 1100 wiring diagrams the first go around; especially since the generalized wiring sketches I saw online of 3-phase R/R's did not include it at all! Most pics of wired-up R/R left the second/middle ouput prong empty. Also, some of these basic diagrams varied fuse placement (see attached for example). What should the fuse placement be with the new R/R, and what rating? Should there be one between the R/R and the switched-on loads? Or between the R/R and the battery positive (which stock it did not have)?

Many thx, again.

QCkaw wrote: Exactly the feedback I was looking for. All good recommendations. Thanks!

I will be doing a rewire, and I think I'll plan to go to 3-phase:
- stator fit for an early 80's 750
- 7AH AGM battery (relatively the same dimensions of the Li, although a few pounds heavier; half the cost of the Li; and settles my nerves given some of the negative feedback I've read about Li/Shorai)
- R/R off a late model Ninja 250
- 3 Ohm coils w/ the Dyna S

And great call on the sensing wire. I didn't notice that looking at the 1100 wiring diagrams the first go around; especially since the generalized wiring sketches I saw online of 3-phase R/R's did not include it at all! Most pics of wired-up R/R left the second/middle ouput prong empty. Also, some of these basic diagrams varied fuse placement (see attached for example). What should the fuse placement be with the new R/R, and what rating? Should there be one between the R/R and the switched-on loads? Or between the R/R and the battery positive (which stock it did not have)?

Many thx, again.

That is a bad place for a fuse. If the fuse blows, the bike may keep running on the charging system, but the battery will be out of the picture. That means the regulator may lose the ability regulate properly (the battery smooths out pulses, as a capacitor would also do). If the bike continues down a highway at speed, the voltage may get to 20 or 30 voltes and you run the risk of melting everything. Even if there are other fuses, the electrical system can be toast. Fuses protect wiring against a short. They do not protect devices from over-voltage or over-current, because the current may not be enough to blow the fuse. People have reported melted headlight bulbs and other damage from having a battery become disconnected while riding.

If a main fuse blows, it should stop the bike, or other damage may occur.

The fuse rating is based on wire capacity, but must also be high enough for the normal bike load with everything on. 20 amps is pretty much standard and safe.

Not all reg/recs need the brown sense lines. Apparently the one in that diagram does not need one (though the whole diagram seems dubious). Most/all of the 2000's era 250/500 Ninjas seem to have the brown wire.








Are you doing a full rewire with gauges and signals?

Call me stupid, but I'm going bare bones; no gages and no blinkers. Will only have headlight and brake/running light.

Thanks again.

Have you ever owned a motorcycle and ridden it on the street; if so, how many years & miles? Do you plan to ride this one on the street? Ed

If you've settled on what you are doing regarding the charge system and ignition, I could draw up a simple bare bones diagram and post it on the Mattylight thread. You can follow the links in my signature to find it.

Riding in the city, most people quickly realize they don't have enough time to look down, and it becomes a distraction to have gauges. Everyone in a car is looking at their phone, and not at you, so you have to spot them first. I rarely find anyone who actually has working gauges in the city (usually that indicates a tourist ).

Yes, I do plan to ride it on the street... Knowing the laws and regulations in your particular state is important, and defines certain requirements for a build.

Over the last 10 years I've owned 3 motorcycles, currently having 2. I also have 3 automobiles, all of which I personally maintain.

Thanks.

The reason I asked is that it sounds like your bike will become a cop magnet. I owned such a bike years ago and couldn't ride more than 5 miles at a time without being stopped and questioned. Maybe NC cops are different than those in MD. :laugh: Ed

Preciate your concern... I think its fair to say they don't care much, given some of the vehicles I've seen on the roads down here.

Here if you don't have the "safety equipment" on the bike that it had when new, they can impound it and make you install all of it before being allowed back on the street.
Steve

I think it is the same here in Colorado for things like turn signals, rear viewing mirror and the like.
Factory installed means compliance with law... Remove and replace with approved state and DOT components is fine, remove them completely and you are breaking the law. At the very least a painful citation.