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Engine turns over, no spark still 25 Jun 2020 09:15 #828958

  • BikeNoob
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Hey guys, I posted a thread two weeks ago that was really helpful and since then I've done some more work on my 78 kz650b but it has failed to started the bike up yet. When I press the push start the bike turns over but just seems to spin and not fully start with no spark to the plugs. My ignition coils are getting full battery power to them and I have just replaced the points/condenser as well. The plug caps and wires are also new as well as the battery. I have been studying the wiring chart but have not been able to pinpoint where my issue may be yet. All the other electrical works on the bike great aside from the ignition system so I am assuming the issue would be in that range as opposed to a start motor issue? What are my best chances of getting this thing started up? I set the gap and timing at the points and after having tested most of the connections to in the ignition system wiring I'm kinda stumped. Only thing I noticed that was weird was that the wiring leaving the contact breaker points have three connections as opposed to the two in the wiring diagram but that might just be the previous owner jerryrigging something? Any further help would be greatly appreciated.
78' KZ650-B2 (Under Construction)

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Engine turns over, no spark still 25 Jun 2020 12:24 #828973

  • Mikaw
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Some bikes have the oil sending unit inside the points housing. That should be the third wire. If you don’t have that then maybe a wire harness was swapped into service that had the third wire...

Three things needed to make a engine run... all need to be confirmed. 1.) spark, 2.) fuel, 3.) compression. Verify all three and the bike will start.

Test the coils. Need an ohm meter and check results against the acceptable range in the FSM. I’ll look to see if I can find one...
1976 KZ 900 A4 kzrider.com/forum/11-projects/613548-1976-kz-900-a4
1976 KZ 900 B1 LTD
1978 KZ 1000 B2 LTD
1980 KZ 750 E1
Kowledge Speaks, But Wisdom Listens.
Jimi Hendrix.
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Last edit: by Mikaw.

Engine turns over, no spark still 25 Jun 2020 12:32 #828975

  • Mikaw
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1976 KZ 900 A4 kzrider.com/forum/11-projects/613548-1976-kz-900-a4
1976 KZ 900 B1 LTD
1978 KZ 1000 B2 LTD
1980 KZ 750 E1
Kowledge Speaks, But Wisdom Listens.
Jimi Hendrix.
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Last edit: by Mikaw.

Engine turns over, no spark still 25 Jun 2020 12:35 #828976

  • Mikaw
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1976 KZ 900 A4 kzrider.com/forum/11-projects/613548-1976-kz-900-a4
1976 KZ 900 B1 LTD
1978 KZ 1000 B2 LTD
1980 KZ 750 E1
Kowledge Speaks, But Wisdom Listens.
Jimi Hendrix.
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Last edit: by Mikaw.

Engine turns over, no spark still 25 Jun 2020 13:28 #828983

  • lakshan
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Did you try actually testing the plugs for spark? If you pull the plug, attach it to the wire and ground the plug against the engine, you should be able to test if you have spark.

Also as Mikaw suggested, I would do a compression test to rule that out.
'77 KZ650B1 in progress...

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Engine turns over, no spark still 25 Jun 2020 23:08 #829017

  • F64
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Hey Bikenoob,
Could you check some voltages at your coil again.
Rotate your engine with a wrench till one of your points is fully open.
The bike ignition switch on.
Put your meter to the 20v DC setting.
Negative meter probe on the negative battery terminal.
Use the positive meter probe to check each of the coil terminals on both coils.
You will have 4 readings.
Then rotate the engine with the wrench till the second set of points is fully open.
Negative meter probe on the negative battery terminal.
Positive meter probe on each of the coil terminals.
Tell us what those 8 readings are.
Don't forget to turn off the ignition switch when you're done with the readings. The coils will overheat if left on for too long.
81-KZ440-D2.
Louis Dudzik's GM HEI ignitor conversion installed 2015 s3.amazonaws.com/gpzweb/Ignition/GPZgmHEImod.html
Motogadget m-unit blue installed 2017.
LIC, NY

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Last edit: by F64. Reason: because i'm a confusing writer before coffee

Engine turns over, no spark still 26 Jun 2020 17:19 #829055

  • F64
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When you hold down the start button, do the points open and close as the engine rotates?
81-KZ440-D2.
Louis Dudzik's GM HEI ignitor conversion installed 2015 s3.amazonaws.com/gpzweb/Ignition/GPZgmHEImod.html
Motogadget m-unit blue installed 2017.
LIC, NY

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Last edit: by F64.

Engine turns over, no spark still 26 Jun 2020 17:44 #829057

  • Scirocco
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Only thing I noticed that was weird was that the wiring leaving the contact breaker points have three connections as opposed to the two in the wiring diagram but that might just be the previous owner jerryrigging something?


The third wire should be connected to the oil pressure switch.

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Last edit: by Scirocco.

Engine turns over, no spark still 27 Jun 2020 13:24 #829115

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Just checked the voltage at my coils again. So with the left, 1-4 points open my readings were as follows: Left coil - (Left Terminal) 10.79 (Right Terminal) 10.79, Right coil - (Left Terminal) 10.79 (Right Terminal) I got .428 but I also got 10.81 a few times so may have just been touching the rubber seal around the terminal. As for the 2-3 points opening measurements I got 12.59v across the board. So I take it this means my 1-4 ignition coil is getting enough juice to start up the bike? What can I check to fix this? The coil is brand new so I don't suspect that is the reason?
78' KZ650-B2 (Under Construction)

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Engine turns over, no spark still 27 Jun 2020 13:26 #829116

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F64 wrote: When you hold down the start button, do the points open and close as the engine rotates?

And yes when the engine turns over the points open and close, I have set the gap as well. They spark a little bit when spinning if that means anything.
78' KZ650-B2 (Under Construction)

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Engine turns over, no spark still 27 Jun 2020 13:47 #829119

  • Mikaw
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Pull all 4 plugs. Put them back into the plug wire caps. Lay them on the engine... make sure off/run is in the run position. Ignition to first station.... clutch lever in and crank the engine... watch for spark plugs to fire... easier in evening or in a closed garage with lights out... your looking for a blue to white colored spark... easiest way to confirm it coils are firing...
1976 KZ 900 A4 kzrider.com/forum/11-projects/613548-1976-kz-900-a4
1976 KZ 900 B1 LTD
1978 KZ 1000 B2 LTD
1980 KZ 750 E1
Kowledge Speaks, But Wisdom Listens.
Jimi Hendrix.

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Engine turns over, no spark still 27 Jun 2020 13:57 #829121

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Mikaw wrote: Pull all 4 plugs. Put them back into the plug wire caps. Lay them on the engine... make sure off/run is in the run position. Ignition to first station.... clutch lever in and crank the engine... watch for spark plugs to fire... easier in evening or in a closed garage with lights out... your looking for a blue to white colored spark... easiest way to confirm it coils are firing...


Coils definitely weren't firing already I think, I tested the 1-4 coils with the screwdriver method and I didn't get any spark there. But I guess the question is that if the coils aren't firing and they are brand new, what could I trace the issue back to?
78' KZ650-B2 (Under Construction)

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