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Pulling throttle too quick cuts out engine when starting 16 Oct 2020 14:04 #837017

  • bSzemanKZ440
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Title says my problem. If I go to pull on the throttle too quick when starting, it'll cut out the engine. If I let go quick enough it won't kill the bike.
What could be causing this? Its an 81 KZ650 CSR
Thanks!
1980 KZ440-B1
1981 KZ650 CSR

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Pulling throttle too quick cuts out engine when starting 16 Oct 2020 14:17 #837020

  • zed1015
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The cause is you are pulling on the throttle too quick.
To fix the problem don't pull on the throttle quick.

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Pulling throttle too quick cuts out engine when starting 16 Oct 2020 14:34 #837021

  • Warren3200gt
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If you crack open the throttle on any carb bike really fast chances are it will stall regardless of under load or not. Fuel is feed to the cylinders by vacuum created by the the cylinder. Air feed to the cylinder by the same vacuum but directly through the slide. So if you crack open the throttle, lifting open the slides, extra air is imediately feed to the cylinder. Extra fuel is feed to the cylinder via the pilot, feed tubes, then into the throttle throat and finally into the cylinder. Result is that the extra air is much more immediate than the extra fuel. Consequently the fuel air mixture is far too lean to combust and the engine cuts out. This is exactly why dfi was developed.

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Last edit: by Warren3200gt.

Pulling throttle too quick cuts out engine when starting 16 Oct 2020 14:45 #837022

  • hardrockminer
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zed1015 wrote: The cause is you are pulling on the throttle too quick.
To fix the problem don't pull on the throttle quick.


You made my day! I was thinking exactly the same!
I have a couple of Z1B's restored, an '80 KZ1000LTD restored, a 1981 KZ550 restored and a 2008 KLR 650 for off road fun. My wife has a 2019 Suzuki DR 650 for on and off road.
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Pulling throttle too quick cuts out engine when starting 16 Oct 2020 16:12 #837027

  • TexasKZ
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You should not be twisting the throttle while starting. Leave it alone. The enricheners will provide the extra fuel needed to start a cold engine. Opening the throttle leans the mixture too much for a cold engine.
1982 KZ1000 LTD parts donor
1981 KZ1000 LTD awaiting resurrection
2000 ZRX1100 not ridden enough
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Pulling throttle too quick cuts out engine when starting 16 Oct 2020 16:40 #837032

  • 650ed
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TexasKZ wrote: You should not be twisting the throttle while starting. Leave it alone. The enricheners will provide the extra fuel needed to start a cold engine. Opening the throttle leans the mixture too much for a cold engine.


Exactly! I've owned my 1977 KZ650-C1 for more than 43 years (more than 62,000 miles) and have never twisted the throttle when starting the bike, and the bike starts up easily every time. If the engine is cold open the choke 3/4 or so, then once the engine starts close the choke.
Ed

1977 KZ650-C1 Original Owner - Stock (with additional invisible FIAMM horn)
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Pulling throttle too quick cuts out engine when starting 16 Oct 2020 17:45 #837037

  • bSzemanKZ440
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Thank you all! That’s a sigh of relief haha.
1980 KZ440-B1
1981 KZ650 CSR

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Pulling throttle too quick cuts out engine when starting 16 Oct 2020 21:04 #837041

  • martin_csr
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Adding to what TexasKZ said, after the engine is warmed up & still warm/hot, when restarting the engine, you shouldn't have to use the "choke", but you may need to crack open the throttle. This stuff in the the owner's manual, Starting the Engine section.

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Last edit: by martin_csr.

Pulling throttle too quick cuts out engine when starting 17 Oct 2020 05:20 #837055

  • Pagala
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If it's still happening after the engine has warmed up, check your spark plugs and see what they show you.
1983 Kawasaki GT550 (UK-only model), also known as the Z550 G1, registered in 1984.

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