1978 z50a electrical

gdk10

Member
Is there any difference in the stator, coil, or magneto of a bike that has a battery and one that does not? My 78 z50a is not wired for a battery and I can still not get more than 2+or-out of the stator directly. A high speed drill will get it to almost 4, but that has got to be close to top rpm.
 

kirrbby

Well-Known Member
The stator makes AC power, so your meter should be set to AC.
Your engine can spin up to...maybe 8 or 9000 rpm. How fast IS your drill?
I think you should be able to see 6 or 7 volts tho...with your drill or whatever.
Our bikes have a coil for the ignition...black wire. And they have a coil for the lighting that is split into 2 "separate" lighting feeds. You would test them separately using the engine case as your ground.
One circuit should be used for the headlight...AC power. The other should go to a rectifier...to be rectified to DC power for a battery circuit...this feeds everything other than the HL.

Do you have a correct wiring diagram for your 78?
It might help to also look at a diagram for a K1 Z50...which DOES have a rectifier and battery in the system. Or a K0 or K3 CT70 diagram.
 

kirrbby

Well-Known Member
I see you already had a thread on this subject.

Might be better to continue in that thread since there is more info in that one...that we can use to try to help you.
 

allenp42

Well-Known Member
The flywheel is the same as prior years - no difference. Stator - Primary coil, which generates the juice for the ignition coil, is the same as prior years; minor difference in the lighting coil but most AFT kits will work fine in a 78.

The voltage out of the coil is a spike when the points open so trying to measure the voltage with a meter, even a good Fluke DVM, is practically impossible. At most, it sounds like your primary coil is good and the points are in fact opening.
 

gdk10

Member
The stator makes AC power, so your meter should be set to AC.
Your engine can spin up to...maybe 8 or 9000 rpm. How fast IS your drill?
I think you should be able to see 6 or 7 volts tho...with your drill or whatever.
Our bikes have a coil for the ignition...black wire. And they have a coil for the lighting that is split into 2 "separate" lighting feeds. You would test them separately using the engine case as your ground.
One circuit should be used for the headlight...AC power. The other should go to a rectifier...to be rectified to DC power for a battery circuit...this feeds everything other than the HL.

Do you have a correct wiring diagram for your 78?
It might help to also look at a diagram for a K1 Z50...which DOES have a rectifier and battery in the system. Or a K0 or K3 CT70 diagram.
Thanks Kirby, my drill is about 7200 rpm but i think i should get about 6v with just my screw gun which is faster than the kick starter. The drill does increase the output about a volt or so Yes I have been measuring ac power, i have even isolated the coil stator from the lighting stator with same results. Yes I have a wiring diagram and have only been using the ignition side and I have only recently connected all the wiring and have tested with a 6volt battery and all works well. I have bought two magnetos off ebay with the same results from those and one from a ct70 I have. I am thinking maybe a bike with no battery may need a stronger magneto than with a battery one. Also I can get a spark from the coil with a rechargeable 6v battery so there seems to be no problems there. also I have tried with two different stators sets, coils, points and condensers and they are all new, and get the same results. have tested both condensers and they charge and discharge properly.
 

gdk10

Member
The flywheel is the same as prior years - no difference. Stator - Primary coil, which generates the juice for the ignition coil, is the same as prior years; minor difference in the lighting coil but most AFT kits will work fine in a 78.

The voltage out of the coil is a spike when the points open so trying to measure the voltage with a meter, even a good Fluke DVM, is practically impossible. At most, it sounds like your primary coil is good and the points are in fact opening.
Thanks, I have been testing for ac voltage which is a more stable reading
 

gdk10

Member
I see you already had a thread on this subject.

Might be better to continue in that thread since there is more info in that one...that we can use to try to help you.
Thanks for the info, i guess it is too late now...
 

gdk10

Member
Before you mounted the new coils to the stator plate did you sand the coating off the coils at the mounting points?
Yes I did, and pulled the motor again and sanded everything more than once. I would think if it was a ground problem I would not get anything. I have connected a 6 volt battery up with everything connected and all lights work as well as connected it to the coil and got spark at the plug with both sets of stators, coils, condensers and points. I have been trying to get proper voltage straight out of the stator at the connector for the wiring. I get blinking light on my light tester so points are working and get varying output voltage going from screw gun to drill from 1.9 to 2.4 +or_ as well as the same 1.9 or so from the kickstarter. I have gone over everything more than once and tried three different rotors, two from ebay and one from and old shot ct70. that is why I m wondering if a non battery bike just needs a stronger rotor than I have... I can usually get just about anything running but this has me stumped. I am trying to locate a running, non battery bike locally that I can try the rotor from. That's all I know that will tell me if it is something else. And thanks for the help...
 

kirrbby

Well-Known Member
Sorry, but I'm going back to the original thread. There is more info to work from...and some pics.
 

kirrbby

Well-Known Member
Not workin for me. I watched a couple tho...but didn't learn anything new. I think @allenp42 should make a YouTube vid for...some of us :whistle:
Including some of the guys who DID make vids. lol
 

kirrbby

Well-Known Member
OK...It works on my laptop. I've seen Mike's before...and it's a good one. Most that I've seen lead you to one problem or another. i.e. no spark...found the problem, and here it is.
But I haven't seen any that take you through EVERYTHING.
i.e. follow the spark from the magnets to the plug...and all the potential failures inbetween. ...and all of the tools and info to test for and find, ANY of those problems.
 
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