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Spark plug color 04 Aug 2022 10:08 #871670

  • Maxbou92
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New kz750 engine. My air fuel gauge doesn’t work.. what are you thinking about my plug. I have running at 60mph for an hour.. 130 main jet, 2 needle of 0.5mm for my set up. 
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Spark plug color 04 Aug 2022 10:35 #871672

  • Warren3200gt
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Z1000J2 somewhat modified!

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Spark plug color 04 Aug 2022 11:42 #871680

  • Maxbou92
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So you think Im lean a bit or?! Do I need to ride more than 1 hour ?! 130 main jet, 2 shims under needles.. pod filters, small porting, 0.06 milled head, 0.5 oversize, 4-1 stock exhaust with open slip on

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Spark plug color 04 Aug 2022 12:00 #871681

  • Warren3200gt
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Rh plug in your picture is def lean.
But the plug colour will only tell you about the mixture at the revs just before you cut the engine. 
Google plug chop.
"A plug chop is a method of testing your motorcycle's air/fuel mixture by reading the spark plug color after cutting the engine at various throttle positions. This allows you to identify which jets you'll need to change or adjust." 

Z1000J2 somewhat modified!

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Spark plug color 04 Aug 2022 12:24 #871683

  • Maxbou92
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Thank you, so I will try 135 instead of 130. Is it dangerous to ride it like that for make my  break out of 5-600km ? 
Engine has only run for 1h since his rebuilt

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Spark plug color 04 Aug 2022 14:07 #871689

  • ckahleer
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Running at 60mph is half throttle at the most. Your mains are not what is restricting fuel at that point. I would raise the needles.
A full speed plug chop would be good to check mains, but I don't know how you do that on a 750.
On my 305 its doable.
 
94 KE100
81 CM200t
82 KZ305
79 KZ400
85 VT 500c
85 VF1100c

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Spark plug color 04 Aug 2022 14:37 #871691

  • Maxbou92
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Thank you guys.. so if I shim the needles again.. I guess it will be rich from 1500 to 3500rpm.. because in this range I feel the engine is near of being top rich.. now with the 1mm raise is pretty limit to that range?! What are you thinking?! When I put more throttle to be in the 4000 to 6000 rpm Its sounds and feel amazing!!  I dont want to put it more for now.. just 100km to ride since the rebuilt!!!! 

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Spark plug color 04 Aug 2022 14:40 #871692

  • Mikaw
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There’s something unusual about the coloring of the earth strap. Did you brush them? 
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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Spark plug color 04 Aug 2022 14:47 #871693

  • Maxbou92
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No I make 100km in total and at the end constant speed at 60mph.. 

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Spark plug color 04 Aug 2022 14:49 #871694

  • Maxbou92
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I forgot to mention ; yesterday it was a  very hot day, don’t know if it change something!

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Spark plug color 05 Aug 2022 09:37 #871719

  • linuxrob
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Best way to check low, med, and full throttle is a dyno run.

here are my plugs with mixtures OK
 
1980 Z500 B2 owned from new 78260 miles
1980 Z500 B2 in bits since 1982 23000 miles
2004 GSF1200S Bandit K4
2000 GS125 ESD
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Spark plug color 05 Aug 2022 09:44 #871720

  • Maxbou92
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How many miles on them?! So I just called a Dyno shop. A good one. The guy say me ; sorry dont have any time to spend on these bike this summer.. cv34 carbs with pod are painfull to tune.. 
so I will try to make my Afr Gauge working!! It say 20 sometimes go to 10 afr ?!! 

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