1979 KZ 650 sr no start no spark

ejsimelaro
Topic Author
Offline
User
Registered
Posts: 5
Thanks: 0

1979 KZ 650 sr no start no spark

07 Sep 2026 06:02

The bike sat over the winter. Come May I started prepping the bike for riding I only have Saturday to work on the bike. Installed fresh fully charged battery and some gas. The bike cranks no start. I started diagnosing the issue. pulled plugs and looked for spark. Nothing. I cleaned the points and tested them for resistance which was the 1st thing I did before doing or order anything No spark, I pulled and bench tested the coils they are over 40 yo all original parts. The Coils from what I could tell were out of spec I don't remember the numbers at this point in time. I am also learning as I go here. I bench tested what I can before I ordered replacement parts on everything I list here. coils, condenser, spart plugs, still no spark, Again, trying to figure this out as I go. So, I am apparently missing something as I have voltage at the coils. Now I tried cranking the bike with the points cover open and I am not seeing a spark at the points when they open and close so I am assuming there is some issue before the points, but I do not know where. I am trying to avoid replacing the points if I don't have to. So anybody who knows more then me have any idea where I can look next to see what the issue is. A lose wire or maybe a short. What would cause no spark if it was not the coils, condenser and spart plugs. Thanks in advance!

Tinker Hobbyist

Please Log in or Create an account to join the conversation.

Wookie58
Offline
Moderator
Registered
Posts: 6878
Thanks: 4330

Re: 1979 KZ 650 sr no start no spark

07 Sep 2026 07:15

#927341

ejsimelaro wrote:

The bike sat over the winter. Come May I started prepping the bike for riding I only have Saturday to work on the bike. Installed fresh fully charged battery and some gas. The bike cranks no start. I started diagnosing the issue. pulled plugs and looked for spark. Nothing. I cleaned the points and tested them for resistance which was the 1st thing I did before doing or order anything No spark, I pulled and bench tested the coils they are over 40 yo all original parts. The Coils from what I could tell were out of spec I don't remember the numbers at this point in time. I am also learning as I go here. I bench tested what I can before I ordered replacement parts on everything I list here. coils, condenser, spart plugs, still no spark, Again, trying to figure this out as I go. So, I am apparently missing something as I have voltage at the coils.What is the voltage at the coils when cranking ?
Now I tried cranking the bike with the points cover open and I am not seeing a spark at the points when they open and close so I am assuming there is some issue before the points, The condenser's only purpose is to reduce arcing at the points but I do not know where.
I am trying to avoid replacing the points if I don't have to. So anybody who knows more then me have any idea where I can look next to see what the issue is. A lose wire or maybe a short. What would cause no spark if it was not the coils, condenser and spart plugs. Thanks in advance! Pull one lead from each coil off the plugs (#3 & #4) put plugs in the leads and lay on the cyl head, switch on ignition, now open the points manually - do you get a spark each time you open the points

1982 KZ1000 Ltd
www.kzrider.com/forum/11-projects/617631...-82-begins?start=192

kzrider.com/forum/faq-wiki/616810-electr...-fault-finding-guide

Please Log in or Create an account to join the conversation.

Warren3200gt
Offline
User
Registered
Posts: 1773
Thanks: 953

Re: 1979 KZ 650 sr no start no spark

07 Sep 2026 07:42

#927342

Has it got a clutch or sidestand lock out switch?

Please Log in or Create an account to join the conversation.

F64
Offline
User
Registered
81-KZ440D2
Posts: 1233
Thanks: 450

Re: 1979 KZ 650 sr no start no spark

07 Sep 2026 08:13 - 07 Sep 2026 08:14

#927343

Did it run last summer?
What have you done to the bike since it was parked?
How and where was the bike stored?

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

Last edit: 07 Sep 2026 08:14 by F64.

Please Log in or Create an account to join the conversation.

gd4now
Offline
User
Registered
Denco where did you go?
Posts: 1718
Thanks: 708

Re: 1979 KZ 650 sr no start no spark

07 Sep 2026 08:31

#927344

Stock it would of come with a clutch lock out switch for power to reach the starter relay. He indicated the starter will turn the engine. So that does not play into the no spark issue.I would as Wookie indicated check for voltage to the coils, and test as he indicated, as it needs to be very near to full battery voltage for them to work correctly. He does indicate that he cleaned the points and installed new condensers though. If not installed correctly they can ground out power to the points.

1977 KZ650 B1
Pods and Denco header

OLD KAW OWNERS SMILE ALOT

The following user(s) said Thank You: Wookie58

Please Log in or Create an account to join the conversation.

ejsimelaro
Topic Author
Offline
User
Registered
Posts: 5
Thanks: 0

Re: 1979 KZ 650 sr no start no spark

12 Sep 2026 09:29 - 12 Sep 2026 09:31

#927468

Thanks for every one's suggestion. My adventures in starting the bike today consisted of checking the voltage at the coils with ignition on and while cracking. with just the ignition on I was seeing 10 + volts the battery is showing over 12 v but as a buffer I hooked up a jump pack to make sure I had enough voltage. During the cranking process volts would drop around 3 to 4 volts this is on each coil. Manually opening and closing the points did not produce spark and they did have voltage around 11 volts. Also I did burn my finger on one of the points I know resistance produces heat so there is resistance at the points based off of my finger heat meter. my thoughts now is maybe it is the points I did make sure that when I replaced the condenser, I put the isolators back in the same position as I took pictures, I always take pictures. Attached is a picture of the old and new condensers wired up

Tinker Hobbyist

Last edit: 12 Sep 2026 09:31 by ejsimelaro.

Please Log in or Create an account to join the conversation.

moizeau
Offline
User
Registered
Posts: 82
Thanks: 61

Re: 1979 KZ 650 sr no start no spark

12 Sep 2026 10:10

#927469

10+ volts at he coils with the ignition isn't enough. Trace the wires and clean the contacts

Please Log in or Create an account to join the conversation.

Wookie58
Offline
Moderator
Registered
Posts: 6878
Thanks: 4330

Re: 1979 KZ 650 sr no start no spark

12 Sep 2026 11:33

#927472

moizeau wrote:

10+ volts at he coils with the ignition isn't enough. Trace the wires and clean the contacts

agreed, you should have within 0.5v of battery voltage at the coils which will drop to around 10v when cranking

1982 KZ1000 Ltd
www.kzrider.com/forum/11-projects/617631...-82-begins?start=192

kzrider.com/forum/faq-wiki/616810-electr...-fault-finding-guide

Please Log in or Create an account to join the conversation.

TexasKZ
Offline
Platinum Member
Registered
Posts: 8403
Thanks: 2789

Re: 1979 KZ 650 sr no start no spark

12 Sep 2026 14:01

#927476

Could be a bad battery. Connect your meter to the battery posts, not the cables. Turn the key on and press the starter button. If it drops below 10 volts, the battery is toast and needs to be replaced.

1982 KZ1000 LTD parts donor
1981 KZ1000 LTD slowly moving toward resurrection
2000 ZRX1100 not ridden enough

www.kzrider.com/forum/11-projects/620336...amateur-build-thread

Please Log in or Create an account to join the conversation.

F64
Offline
User
Registered
81-KZ440D2
Posts: 1233
Thanks: 450

Re: 1979 KZ 650 sr no start no spark

12 Sep 2026 19:53 - 13 Sep 2026 09:18

#927484

Grab your volt meter
set the meter to DC V

turn the key ignition on
kill switch set to "RUN"
bike not running

put your red probe on battery negative terminal (metal part of battery)
black probe on the nut marked by the pink arrow while pushing the points apart(marked by red arrow).
what is your reading?
close to 0.0V or close to 10V?

move your black probe to the green arrow nut and press the points apart( marked by yellow arrow)
what is your reading?

is the black wire from one of the condensors touching the rotor?

turn off bike

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

Last edit: 13 Sep 2026 09:18 by F64.

Please Log in or Create an account to join the conversation.

ejsimelaro
Topic Author
Offline
User
Registered
Posts: 5
Thanks: 0

Re: 1979 KZ 650 sr no start no spark

11 Oct 2026 14:30

#928473

Sorry for the delay in responding. I been unable to work on the bike till this past Saturday. So battery voltage does not drop below 10v when cranking, I also get 10 to 11 volts at the points. So, I think I have a wiring harness issue. I put my multimeter negative on the battery and the positive on the harness before the coils. Battery voltage shows 11+ volts until I start to crank the bike. The volts drop to 7 while cranking. I did some googling and that is way to low of a voltage for the coils to do anything. So if nothing prevents me from working on the bike next weekend, I am going to see if I can find out where the issue is in the wiring. My understanding is power flows from the battery to the fuse box. I did upgrade the fuse box to a modern blade style so maybe that is the issue. Then it goes from the fuse to the ignition key then kill switch and then coil. I am pretty sure I tested the fuse box and had 12 volts going across the wire, but I don't remember at this point for sure. Thanks again.

Tinker Hobbyist

Please Log in or Create an account to join the conversation.