New plunger black plugs

  • Nessism
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Re: New plunger black plugs

22 Jul 2025 07:23
#914947
Several model of Suzuki GS bikes used richer main jets in the center two carbs compared to the outside carbs.  Airbox flow?  Maybe.  I assumed it was because of cooling differences, with the center cylinders running hotter.  Anyway, one step difference on the mains shouldn't be a dealbreaker.  Of course, the proof is in the doing, and this bike shows rich on the center cylinders, particularly #2.  Something may be wrong outright with that carb.  
Ed
Carb O-ring Kits : www.kzrider.com/forum/3-carburetor/61807...-o-ring-kits?start=0

www.kzrider.com/forum/faq-wiki/618026-new-owner-things-to-know

1981 KZ750E2
www.kzrider.com/forum/11-projects/604901...z750e-project-thread
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Re: New plunger black plugs

22 Jul 2025 07:40 - 22 Jul 2025 07:42
#914948
Nessism wrote:
Several model of Suzuki GS bikes used richer main jets in the center two carbs compared to the outside carbs.  Airbox flow?  Maybe.  I assumed it was because of cooling differences, with the center cylinders running hotter.  Anyway, one step difference on the mains shouldn't be a dealbreaker.  Of course, the proof is in the doing, and this bike shows rich on the center cylinders, particularly #2.  Something may be wrong outright with that carb.  
I remember broaching this topic a long time back and I got "shot down" for even suggesting it. Many years ago I ran the centre cylinder on my KH400 (with pods because the mono shock filled the air box space) richer - 1 slot on the needles - and it ran perfectly with even coloured plugs (I appreciate the centre cylinder running hot was more of an issue with the 2 stroke triples)
1982 KZ1000 Ltd
www.kzrider.com/forum/11-projects/617631...-82-begins?start=192
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Last edit: 22 Jul 2025 07:42 by Wookie58.
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Re: New plunger black plugs

22 Jul 2025 07:44
#914949
Thank you man.. all is done with these carbs!! Ultrasound cleaning, mechanical synchro.. a lot of valve has been corrected by machinist before my rebuilt.. last guy has make wrong timing and bent a few valve!! Now everything is on specs.. dont know what to do, I will try to put 102.5 instead 105 like Zed suggest me.. last night I took hot compression.
1 : 165
2 : 163
3: 157
4: 160
Kz750e 1980
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Re: New plunger black plugs

22 Jul 2025 08:27
#914951
One other thing to try...

Remove the spark plug caps on the center cylinders, and measure resistance.  They unscrew from the wires.  Should be something in the range of 5000 ohms.  Inspect the spark plug leads, and snip off about 5mm off the end, before screwing the caps back on.  If the cap shows high resistance, you can use a flat blade screwdriver, and open up the cap, for checking the resistor inside.
Ed
Carb O-ring Kits : www.kzrider.com/forum/3-carburetor/61807...-o-ring-kits?start=0

www.kzrider.com/forum/faq-wiki/618026-new-owner-things-to-know

1981 KZ750E2
www.kzrider.com/forum/11-projects/604901...z750e-project-thread

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Re: New plunger black plugs

22 Jul 2025 08:40
#914954
4600-4700 ohms on each one!! But I cant see clearly wires inside .. do I need to remove some rubber to see some wires?!
Kz750e 1980
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Re: New plunger black plugs

13 Aug 2025 16:01
#915928
As Nessism said, snip off a finger width from the coil end of the wire, thus allowing for fresh new snug contact, over time the connection will get molded to that form inside the wire, then road/engine vibrations loosens that molded form just a smidge, causing an intermittent connection issue. Put a small dab of dielectric grease on the end before screwing back into coil.
1982 KZ1100D1

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Re: New plunger black plugs

13 Aug 2025 16:04
#915929
Thank you!! Its done. Plugs are still black a bit, but the bike runs great
Kz750e 1980

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