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KZ440 Carb Issues 26 Sep 2022 19:21 #874653

  • FreshMark
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Hello, 
I am trying to start my 1980 KZ440A and am having some trouble.  The bike is getting spark, and the timing seems correct (enough) that it fires on starting fluid.  With the carbs full of gas, I am unable to get the bike to start or even fire.  The spark plugs seem to be totally dry.  Does this indicate a problem with the pilot jet?  I also had the carb intake completely open since I was having trouble getting the airbox boots on.  
Thanks

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KZ440 Carb Issues 26 Sep 2022 19:54 #874655

  • Nessism
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You might want to read through this to see if anyone applies...

www.kzrider.com/forum/forum-index/faq-wi...owner-things-to-know
Ed

Carburetor O-ring Kits For Sale: Mikuni VM & BS/CV, and Keihin CV34 (as used on KZ750E/H/N/Spectre, 400)

www.kzrider.com/forum/forum-index/faq-wi...owner-things-to-know

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

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KZ440 Carb Issues 18 Oct 2022 17:25 #875690

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Dumb question, but should the bike start without being connected to the airbox?  

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KZ440 Carb Issues 18 Oct 2022 18:02 #875691

  • Mikaw
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It should start but will be lean. Have confirmed the choke is working? Is the fuel fresh? Have you done a compression test? Have you removed the float bowls to visually look for debris or corrosion? Engines need fuel/air, spark, and compression to run. You state the carbs are full, that must mean the fuel is not getting pulled into the cylinders. You have spark. You need to confirm compression. 
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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KZ440 Carb Issues 18 Oct 2022 18:09 #875692

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The choke flaps do actuate if that’s what you mean. I am able to get it to fire on just starting fluid, but it is difficult (could be because airbox boots weren’t connected to carbs and I sprayed into airbox). 

from what I can tell compression is fine. It pulls suction through the intake and when I cover the spark plug hole with my thumb It pushes my thumb out. 

How can I check if fuel is getting to the engine?
 

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Last edit: by FreshMark.

KZ440 Carb Issues 18 Oct 2022 18:13 #875693

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Plugs will be wet. 

Spraying starting fluid into the air box is acceptable. Put you palm over the carb opening while cranking the engine on the starter. You should feel significant suction. 

How do you know the carbs are full?
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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KZ440 Carb Issues 18 Oct 2022 18:16 #875694

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I am just assuming they are since the one began leaking through the overflow tube (needle valve isn’t seating properly so I just shut the petcock). Both carbs have fuel, however it might not be enough to submerge the jets?

I also wonder if loosening the mixture screw will help since you mentioned the ratio will be lean. I can try to crank the bike to test vacuum tomorrow

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KZ440 Carb Issues 18 Oct 2022 18:26 #875695

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You have a carburetor problem. Trying to get this bike running will be difficult. Carburetors problem will not fix themselves. Your time will be better spent fixing the carbs than trying to get it started. 

How long did the bike sit without running. With the alcohol in the fuel today it doesn’t take long for it to attract moisture and corrosion to start. 

Not to sound rude but assumption is not a diagnostic method.
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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Last edit: by Mikaw.

KZ440 Carb Issues 18 Oct 2022 18:44 #875696

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I’m not entirely sure. I know it ran when it was parked and it was maybe early 2000s sometime. Not sure if the gas was drained or left to sit in the carbs. 

I did get a carb rebuild kit, and swapped out the secondary jet and needle valve. Unfortunately the pilot jet threads were too large and wouldn’t fit. I made sure that I could see through each of the 3 jets before reassembly and I sprayed the passageways good with carb cleaner. What else should I look at?

You’re right about assuming things. This is the first bike I’ve worked on so it’s a learning experience. 

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KZ440 Carb Issues 18 Oct 2022 19:09 #875697

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Carb “kits” are not the best option. 99% of the time the brass (Jets, seats) are good and only require cleaning. Kits are designed to cover as many different carbs with the minimum number of different kits. If that statement makes sense. I mean not all parts will be needed in the kit or actually correct. Hopefully you kept all your old parts. Most carb rebuilding can be done cleaning and reusing the brass and just replacing the O-Rings and caskets. Spray and pray isn’t a a guarantee that all passages are clear. Fuel in the overflow tube could be a cracked overflow tube, not necessarily a true overflow. Nessism, Zed1015, and gd4now are our local carb experts. I’m not familiar with your specific carburetors. I’d pull the carbs, break them down and soak them in carb dip, clean your old brass, install them, get new gaskets and O-Rings. set the float levels, and set pilots to factory settings.
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.
The following user(s) said Thank You: Nessism

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KZ440 Carb Issues 18 Oct 2022 20:40 #875698

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Carb “kits” are not the best option. 99% of the time the brass (Jets, seats) are good and only require cleaning. Kits are designed to cover as many different carbs with the minimum number of different kits. If that statement makes sense. I mean not all parts will be needed in the kit or actually correct. Hopefully you kept all your old parts. Most carb rebuilding can be done cleaning and reusing the brass and just replacing the O-Rings and caskets. Spray and pray isn’t a a guarantee that all passages are clear. Fuel in the overflow tube could be a cracked overflow tube, not necessarily a true overflow. Nessism, Zed1015, and gd4now are our local carb experts. I’m not familiar with your specific carburetors. I’d pull the carbs, break them down and soak them in carb dip, clean your old brass, install them, get new gaskets and O-Rings. set the float levels, and set pilots to factory settings.


Agree with breaking down the carbs, and cleaning them properly.  I've got all the o-rings you might need to do the job.  "Carb Kits" rarely have the right parts, and never all the O-rings.
Ed

Carburetor O-ring Kits For Sale: Mikuni VM & BS/CV, and Keihin CV34 (as used on KZ750E/H/N/Spectre, 400)

www.kzrider.com/forum/forum-index/faq-wi...owner-things-to-know

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

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KZ440 Carb Issues 19 Oct 2022 04:19 #875702

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What do you mean by set the float level?  Is that bending that little tab that holds the needle?

Thankfully, I was smart enough to keep the old jets that I had removed. 

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