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#4 spark plug dark soot fouls every time

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22 Aug 2022 04:57 #872640 by KD
#4 spark plug dark soot fouls every time was created by KD
I need help; my #4 spark plug fouls every time I ride my 75 Z1B. I have had the engine bored out and leak tested, I have had the carburetors re-jetted and tested, I have also repowered the coils last week. I am hitting a brick wall and need some other Ideas

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22 Aug 2022 06:59 #872643 by Warren3200gt
Replied by Warren3200gt on topic #4 spark plug dark soot fouls every time
No 4 choke plunger seal?
No 4 inlet valve seal? 
No 4 float height? 
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Z1000J2 somewhat modified!
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The following user(s) said Thank You: Nessism, KD

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  • howardhb
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23 Aug 2022 03:15 - 23 Aug 2022 03:16 #872671 by howardhb
Replied by howardhb on topic #4 spark plug dark soot fouls every time
Pure Bike Porn.....
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That chain guard is interesting!
 
'81 GPz 550 D1
'81 GPz 1100 B1 ELR "Tribute" www.kzrider.com/11-projects/617040-1981-...-rstomod-elr-tribute
'82 Yamaha YB100 Fizzie
'79 Suzuki GT200 X5 TWO STROKE TWIN - SMOKER!
Last edit: 23 Aug 2022 03:16 by howardhb.

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23 Aug 2022 08:44 - 23 Aug 2022 12:06 #872691 by Warren3200gt
Replied by Warren3200gt on topic #4 spark plug dark soot fouls every time
Chain guard? You talking about the J2 Howard?

Sorry for the meander away from topic KD. 
[img
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[img

Z1000J2 somewhat modified!
[img

Last edit: 23 Aug 2022 12:06 by Warren3200gt.

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24 Aug 2022 14:49 #872772 by KD
Replied by KD on topic #4 spark plug dark soot fouls every time
So if the plunge router is the issue than it stays open and allows too much fuel in?

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24 Aug 2022 14:59 - 24 Aug 2022 15:03 #872774 by Warren3200gt
Replied by Warren3200gt on topic #4 spark plug dark soot fouls every time
The choke plunger has a seal at the bottom which closes off the choke pick up tube when the choke is off.  If the seal is knackered the choke will be constantly partially open on that carb/cylinder.
 
[img
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[img

Z1000J2 somewhat modified!
[img

Last edit: 24 Aug 2022 15:03 by Warren3200gt.

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24 Aug 2022 15:02 #872776 by KD
Replied by KD on topic #4 spark plug dark soot fouls every time
Okay that sounds promising, I’ll give it a go! Thank u

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24 Aug 2022 18:21 #872791 by KD
Replied by KD on topic #4 spark plug dark soot fouls every time
I switched out the choke plunger for another one I had on an extra set of carburetors, did not make a difference although I noticed the two manifolds in the center did not get hot and the outside pipes were hot so I might have a coil issue

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24 Aug 2022 21:43 - 24 Aug 2022 21:46 #872799 by F64
Replied by F64 on topic #4 spark plug dark soot fouls every time
You may have that #4 spark plug circuit shorting out.
Swap out the spark plug and it's wire to it's complimentary cylinder.
Don't forget to swap the spark plug as well.  Plugs can internally short out.
Measure header temps.
 
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: 24 Aug 2022 21:46 by F64.
The following user(s) said Thank You: KD, BCScott

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25 Aug 2022 17:21 #872861 by KD
Replied by KD on topic #4 spark plug dark soot fouls every time
I did this and the the some side fouled the plug , it didn’t follow with the wire

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26 Aug 2022 12:47 #872907 by F64
Replied by F64 on topic #4 spark plug dark soot fouls every time
It's most likely not the coil.
It's possibly the carb.
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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