#4 spark plug dark soot fouls every time

  • KD
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#4 spark plug dark soot fouls every time

22 Aug 2022 04:57
#872640
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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  • Warren3200gt
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Re: #4 spark plug dark soot fouls every time

22 Aug 2022 06:59
#872643
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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Re: #4 spark plug dark soot fouls every time

23 Aug 2022 03:15 - 23 Aug 2022 03:16
#872671
Pure Bike Porn.....
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That chain guard is interesting!
 
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'81 GPz 1100 B1 ELR "Tribute" www.kzrider.com/11-projects/617040-1981-...-rstomod-elr-tribute
'82 Yamaha YB100 Fizzie
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Last edit: 23 Aug 2022 03:16 by howardhb.

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Re: #4 spark plug dark soot fouls every time

23 Aug 2022 08:44 - 23 Aug 2022 12:06
#872691
Chain guard? You talking about the J2 Howard?

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

Z1000J2 somewhat modified!
[img

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

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Re: #4 spark plug dark soot fouls every time

24 Aug 2022 14:49
#872772
So if the plunge router is the issue than it stays open and allows too much fuel in?

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Re: #4 spark plug dark soot fouls every time

24 Aug 2022 14:59 - 24 Aug 2022 15:03
#872774
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
[img
[img
[img
[img

Z1000J2 somewhat modified!
[img

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

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Re: #4 spark plug dark soot fouls every time

24 Aug 2022 15:02
#872776
Okay that sounds promising, I’ll give it a go! Thank u

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Re: #4 spark plug dark soot fouls every time

24 Aug 2022 18:21
#872791
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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Re: #4 spark plug dark soot fouls every time

24 Aug 2022 21:43 - 24 Aug 2022 21:46
#872799
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.
 
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Last edit: 24 Aug 2022 21:46 by F64.
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Re: #4 spark plug dark soot fouls every time

25 Aug 2022 17:21
#872861
I did this and the the some side fouled the plug , it didn’t follow with the wire

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Re: #4 spark plug dark soot fouls every time

26 Aug 2022 12:47
#872907
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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