kz650 B melting coils

Hi all ... Im the "proud" owner of a late 70s z650 hardtail chop... uncle bunt frame. Have owned her the last twenty years. Recently changed the engine to a B model and made the necessary change to different model rectifier/ reg .. was told i needed the american model one ?? All seems good on the charging system but Im now melting coils. The wiring is far from standard and I believe i have F model coils or similiar ... with the screw on caps so I could fit non standard length HT leads. Will post pics of my baby soon.

My questions are : Why would the coils melt ? gone through three and they all give out on the junction where the bolt tab joins the main body ?
Do I need to fit the B model coils? a coil is a coil right ? or wrong ? I have picked up some B model ones but will have to change mounting point / wiring as factory fitted HT leads not long enough ? Can oneone tell me if the F model has the same resistance as the B or point me in the right direction .. local Kwak dealers / motorbike shops wont touch her and sitting staring and praying is nt helping me .. many Thanks Adam

You might want to look in the factory Kawasaki service manual to see what resistance the coils should be. The resistance level typically matches to the type of ignition system you are using and there are differences depending on if you are using points or an ignitor ignition system. If you don't have a manual you can download one for free here... www.zedrider.co.uk/service--owners-manuals.html

Not sure if you have a points, or electronic ignition.
If you have points ignition and you have the ignition switch on and the engine stop switch on, with the bike not running a coil may get hot. This is because if the points are closed there will currant flow to the coil.
Not sure if it’s the same for bikes with electronic ignition.
Anyway, I noticed this with my Z650B1, so if I have the ignition switch on and the bike is not running, I always make sure the engine stop switch is off.
Also, for points ignition the coil primary resistance will be about 4 Ohms. For electronic ignition it will be about 2 to 3 Ohms.
Brian

Thank you Nessism will have a look

Thanks Brian

Its electronic ignition. Unfortunatly no kill switch, the electrics have been stripped back.

What causes the melting in the first place ? will try and post some pics this afternoon

I had that happening years ago. Faulty voltage regulator. Put a late model R/R on it and the problem went away.
Steve

adbz650 wrote: ... electrics have been stripped back.
What causes the melting in the first place ?....

Would suspect that an internal short could cause the melting, or where the coil is allowed for whatever reason to receive continuous battery voltage even when the engine isn't running or in the process of being started (one example would be inadvertently leaving the ignition switched ON when parking the bike).

My Z1 coil failed one time while riding in Yellowstone, where inspection revealed melted black goo oozing from the old original coil. Not roadside-repairable absent a spare coil, but thankfully a Z1 can motor along quite capably while hitting on just two cylinders. And in this case until locating another coil. Which was all it took, and thankfully without being associated with the regulator/rectifier or wiring incident to the regulator/rectifier.

When traveling with another Z1 rider, where both coils crap out on one of the bikes, a less risky alternative to towing (difficult without a rope, but not impossible) , one good coil may be pirated from the other bike and temporarily installed whereby ride-ability of both bikes may continue.

Then there's always the option of parking and securing the disabled bike as best as possible and continuing as a passenger on your traveling buddy's bike --- a likely fave when it's dark and wolves have started howling. :woohoo:
Shoo, wolf. or I'll sic this Dyna-S on ya!

"Harley Helper" (KZ900 LTD)



Good Fortune!

Electronic ignition models should not even energize the coils if it's not running. If they melt with the ignition turned on, but the motor not running, then the ignition module has a short, or a wire is shorted somewhere.

If you are running electronic ignition coils with points, that could cause them to heat up quite a bit, but the points would also be wearing pretty fast.

The older points system uses 4 ohm coils.
The electronic ignition system uses 2.3 ohm coils.
They should not really be interchanged.

Hi Thanks Loud

Its running a new newtronic electronic ignition system .. I just put volt meter on the coils and they are live with ignition on but motor not running ?? Have checked wiring but no obvious short ... will keep looking.

Whats bit about not being interchangeable .. Im looking at getting a pair of coils off the F model... the screw on caps will allow me to fit the longer HT leads I need.. all help and advise greatly received and appreciated

I'm not familiar with the Newtronic ignition for KZ's. The only one I've dealt with was on an RD400.

You will have to refer to their literature to figure out what coils you need, with regards to ohms.

If the coils have 12v on one primary wire, and near zero volts on the other primary wire, with the motor not turning, the coils can overheat.

Have checked Newtronic site .. recommends 4 ohms .. minimum 3 ohms .. will check what Im getting out of the melted coils and a set of B model ones I have to test the system but will still go through with changing to a different model coils as I need the extra HT lead length i can get from the screw in caps at the secondary end.