Welcome, Guest
Username: Password: Remember me
  • Page:
  • 1

TOPIC:

Intermittent spark 07 Jul 2020 07:03 #830000

  • Ramchargerjay
  • Ramchargerjay's Avatar Topic Author
  • Offline
  • User
  • Posts: 23
  • Thank you received: 0
My 77 KZ750 twin has intermittent spark on cylinder 1 but consistent spark on cylinder 2. Any suggestions?

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

Intermittent spark 07 Jul 2020 07:58 #830003

  • KZJOE900
  • KZJOE900's Avatar
  • Offline
  • Admin
  • Posts: 1971
  • Thank you received: 443
Check for leaky spark plug wire arcing across to the head. Especially if it is more prominent as you increase the rpm's.
Current project 76 KZ900 (This was a Vetter model)
76 KZ900
81 XJ550H SECA (Current Project)
82 XJ550R SECA
Past:
86 FJ1200
74 Z1900
72 CB450

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

Intermittent spark 07 Jul 2020 08:19 #830004

  • F64
  • F64's Avatar
  • Offline
  • User
  • 81-KZ440D2
  • Posts: 1006
  • Thank you received: 335
What do your spark plugs look like?
Have you done a compression check?
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

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

Intermittent spark 07 Jul 2020 10:34 #830021

  • Ramchargerjay
  • Ramchargerjay's Avatar Topic Author
  • Offline
  • User
  • Posts: 23
  • Thank you received: 0

F64 wrote: What do your spark plugs look like?
Have you done a compression check?


Compression is 135 on cylinder 1, 145 on cylinder 2. Plugs are carbon fouled.

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

Intermittent spark 07 Jul 2020 13:54 #830044

  • F64
  • F64's Avatar
  • Offline
  • User
  • 81-KZ440D2
  • Posts: 1006
  • Thank you received: 335
You could run hotter plugs, but that's just a bandaid.
Unless, you don't mind running rich.
Which plugs are you running?

Have you done anything to the carbs or the intake side of the engine?
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

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

Intermittent spark 07 Jul 2020 15:57 #830056

  • Ramchargerjay
  • Ramchargerjay's Avatar Topic Author
  • Offline
  • User
  • Posts: 23
  • Thank you received: 0

F64 wrote: You could run hotter plugs, but that's just a bandaid.
Unless, you don't mind running rich.
Which plugs are you running?

Have you done anything to the carbs or the intake side of the engine?


NGK B7E S plugs
Filter pods, #52 pilot jets, 140 main jets. Cleaned carbs and checked float height

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

Intermittent spark 07 Jul 2020 17:10 #830058

  • F64
  • F64's Avatar
  • Offline
  • User
  • 81-KZ440D2
  • Posts: 1006
  • Thank you received: 335
Well, without knowing your mixture at different parts of the carburetor circuit, it's hard to suggest jets and needle positions.
You could do plug chops on new plugs and that would get you to see what the carbs are doing in each circuit.

Plugs
The factory states anywhere from a B8ES to a B6ES.
See if you grab a pair of B6ES.
The plug will run hotter preventing the fouling.
You can also close the gap to make it easier on the ignition system to fire the plug.
Run your point gap to the smaller end of the spec. It may be .3mm. This will give your coil a bit more of a charge.
Check timing to make sure the gap adjustment didn't shift your timing


What you are trying to do is keep the tip of the spark plug above 900 degrees Fahrenheit but below 1600f.
If the tip of the plug is below 900f, you will foul the plug. Above 1600f and the plug will cause pre-ignition.


Photo:https://www.sparkplugs.com/Data/uploads/Charts/NGK_Plug_Chart_1.jpg

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
Attachments:
The following user(s) said Thank You: Ramchargerjay

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

Last edit: by F64.

Intermittent spark 16 Jul 2020 19:17 #830841

  • BobberDan
  • BobberDan's Avatar
  • Offline
  • User
  • Posts: 26
  • Thank you received: 0
Just went thru that with my 79. Took me 2 weeks of tinkering and brain work . Bet a dollar your timing is off a tiny bit...First step is adjust timing chain tensioner. . 2 set points. And static timing . If that don't solve it loosen point plate just enough that you can yep with a tool and move it and I think I advanced it a C hair (while running) and bingo run perfect and has all season ... If I remember I rotated point plate clockwise.... and check and recheck point settings

Attachment not found

Attachment not found

Attachment not found

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

Intermittent spark 16 Jul 2020 19:24 #830842

  • BobberDan
  • BobberDan's Avatar
  • Offline
  • User
  • Posts: 26
  • Thank you received: 0
Your timing is off ...here what I did to diagnosi..moved point plate while running. Think it was clock wise and bingo..adj timming chain tension triple check points. I chased same problem for a week or 2 ... 79 kz750 twin...has run perfect all season sense
Attachments:

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

Intermittent spark 16 Jul 2020 20:32 #830845

  • 650ed
  • 650ed's Avatar
  • Offline
  • User
  • Posts: 15344
  • Thank you received: 2828

BobberDan wrote:


Australia? :laugh: Ed
1977 KZ650-C1 Original Owner - Stock (with additional invisible FIAMM horn)

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

Intermittent spark 21 Jul 2020 08:32 #831114

  • Ramchargerjay
  • Ramchargerjay's Avatar Topic Author
  • Offline
  • User
  • Posts: 23
  • Thank you received: 0
Thanks everyone for your input. I had set the points and timing right already. I replaced the coil and it fixed it.

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

  • Page:
  • 1
Powered by Kunena Forum