TOPIC:

Hey guys, I wanted to run through a problem here before i buy a bunch of expensive parts that may not fix the problem. Heres the skinny,

KZ650B2 - has Dyna III ignition, brand new reg/rec, coil mod. New battery.

The problem - Bike will start right up when battery is fully charged and runs great, a short ride to the store and the bike will not start on the button but will kick start first try. riding further and stopping and then restarting will require 15 min of kick-starting to get running and battery is pretty much dead. The battery has been replaced a few times. It seems as if it is a charging problem, however it only started once the coil mod was done.

I have checked the connections and wiring on the coil mod, its seems sound. I have checked the output of the dynamo and its 60-65V at 4000RPM, which is low. I also checked the resistance between the yellow wires and it is 0.6 ohms. all of this seems to point to the stator being bad, but it was completely fine fine until the coil mod was done. Is it possible that by supplying the coils with the proper amount of voltage the charging system can no longer keep up with the aftermarket ignition I have read this is a common issue on single phase kz650s.

If this is the case I plan on swapping for a 3 phase stator and reg/rec as has been well documented here, I just wanted to get a second opinion here before I spend $160 on parts.

Is there anything else I should look at?

thanks!

what reading are you getting on a multimeter across the battery poles with the engine running a few k rpm?

Warren3200gt wrote: what reading are you getting on a multimeter across the battery poles with the engine running a few k rpm?

Should be 14-14.5 vdc at 5000 rpm if the system is functioning right.

Different bike than mine, but same principals apply. The starter may also be dragging or bushings ruining dry. Perhaps the coil mod is applying too much voltage somewhere else. Have you tried removing it or taking a look inside the starter?



This is at ~4K rpm on a older AGM battery, (2-3 years old) that kicks it over easily.


My service manual calls for <15 vdc @ 4K rpm. I feel that 15 VDC charge rate is too high, IMHO.

Hey Vic, this problem has been haunting Kzrider since the earliest days. You may have seen the posts on it. (along with the 3-phase conversion info).

To summarize:
Basically, what it comes to is that some of the 78 and 79 Kz650's had charging systems that were a bit weaker than others. Not all of them though. And they were ok with the stock electrical system. The 60-65 VAC open load test confirms the slight weakness. It really should have been closer to 70 or even 75 VAC.

When a Dyna III or Dyna S ignition gets installed, the slight weakness in the charging system results in a slow average drain on the battery when running. Even if it seems to charge initially or at some times, with heat and over time, the alternator just seems to not quite keep up with the load. It doesn't seem to matter what regulator/rectifier is used. The Dyna III and Dyna S have a much longer dwell so they use much more average current than the stock points. If you are running 3 ohm coils, that makes the ignition use even more current. The coil relay mod will likely cause a slight current increase over old wiring given the same Dyna ignition and coils setup.

The solution has been to use a 3-phase stator from a later Kz650 or Kz750four... or aftermarket 3-phase stator. And of course to then go to a 3-phase reg/rec. Luckily, you can get a used, but much newer. 3-phase Kawasaki factory reg/rec for about $10 from a 2000's Ninja. Martin and I have been using them for some time. And of course you can install one of the newer series-pass Shindengen reg/recs, but they cost a bit more.

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Since I know you are meticulous, I was hoping you could do a quick analysis of your rotor while you are troubleshooting this problem. Because it's been an issue for so long, I've always tried to come up with ideas why it's some 78 and 79 Kz650's but not all of them.

My most recent thought was about the magnets in the rotor. I think the 78 and 79 Kz650's were the first to get the cup-shaped magnetic rotor/flywheel. The cup keeps them from flying out. In the cup are 4 magnet sections. Each with multiple poles. I believe the magnets can get installed backward. If one is backward, it would reduce charging power by some percentage, but it may still have enough to power for a stock points bike.

I believe this may have been an issue and it's what caused Kawasaki to re-engineer the cup-shaped rotor with 3 magnet sections (instead of 4) on later bikes including the 550's and some/all 750fours. With the 3-magnet section type, the magnet section can be installed in either way and the poles still line up appropriately.

If you have the time and feel up to it, I'd like to know if one of your rotor magnets might be backward. To find out you just run a small magnet along the inside of the rotor and count how many times it flips as it passes over the multiple poles. There will be a pattern to how the magnet flips.

I will post a diagram and video when I get a chance. They will better illustrate what I'm talking about.

If it turns out the rotor has a magnet reversed (again, it's just a guess on my part) then a new rotor would probably be on the menu as well.

Coincidentally, user moroboshi1196 has a bad stator and I'm talking him through the 3-phase solution currently as well.
kzrider.com/forum/4-electrical/610736-bad-stator

I had similar problems when I discovered my stator was shorted. I had been charging the battery prior to getting my therapy in, but it was starting poorly and almost stranded me a few times. Especially if I took a ride down a long local road, with a lot of stop lights and low revs. (headlight and 2 1157 brake lights on a lot + the usual tail / instrument lights) I was assuming the one year old battery had failed already, so kept charging my battery every time I parked it, and I was thinking I needed to buy another battery too soon.

I had spare some time one day to check things closer so I started going through a bunch of the charging system testing.. Stator output, impedance, check the R/R, brown sense wire etc.. It was charging fine, or seemed to be, yet the battery went down slowly while I rode. As it turned out my stator still output AC voltage, but was shorted to chassis. Once I changed the stator, then I was seeing excessive charging, except my battery was no longer going dead as I rode. I found the Brown sense wire to the regulator was not at full B+ voltage, hence regulator output was high. I corrected that with a ice-cube relay. It has been trouble free ever since with the same battery that was going dead. I had already replaced what may have been a good battery a year before.


Unless you absolutely NEED the "mod" on the ignition, perhaps using it for the sense wire voltage may work better in your case. My bike seems to zing up fine on the stock ignition wiring.


The cooked stator.


Loudhvx brings up some excellent points and a deficiency in charge current could certainly account for starting /charging problems. I would suggest a real close look at the entire setup, and possibly make a few changes to the OEM setup.

Hey guys thanks for the replies. This is actually my buddies bike that I have been working on and off for a few years but now he lives in another state so I'm walking him through this over the phone. I had him buy a 3 phase stator and a ninja R/R.

I will have him try the battery test to see what turns up. Thanks again!

Just wanted to update here. This was indeed the problem. I helped my buddy switch to 3 phase via Facetime and the bike now runs great no problems. Unfortunately we forgot to do the magnet test. Thanks again for the replies!