KZ200, no idle warm, hard to start warm.

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19 May 2024 09:59 #899303 by LasseT
KZ200, no idle warm, hard to start warm. was created by LasseT
I have a KZ200 -80 with original rebuilt carburetor.
It starts easy cold and runs with a decent idle, but when warm the idle goes down and if I stop it its hard to restart. If warm I can start it by running with the bike, but not with the kick and hardly with the electric starter. If it cools for 10-15min it start easy.
 

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19 May 2024 13:06 #899311 by Wookie58
Replied by Wookie58 on topic KZ200, no idle warm, hard to start warm.
When was the oil last changed ?
Can you do a compression check when hot (could be a sticking valve)
Hot starting issues would often be down to one of the below
  • Weak mixture
  • Poor compression (siticking valve etc)
  • Engine is tightening up when hot (possibly too hot) then eases as it cools
1982 KZ1000 Ltd
www.kzrider.com/forum/11-projects/617631...-82-begins?start=192
kzrider.com/filebase-alias?view=download...d-fault-diagnosis&ca
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20 May 2024 13:50 #899396 by LasseT
Replied by LasseT on topic KZ200, no idle warm, hard to start warm.
Hi,
oil changed ~1300km
Spark plug a bit dark an fuel consumption a bit high, ~0,5l/10km
Maybe not right term in english? Flat grinded cylinder head ~1mm
Compression ~7kg
Ignition adjusted after fixing cylinder head.

The bike has never run better than now, easy 90km/h with me ~100kg
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20 May 2024 14:14 #899397 by Rolf1976_KZ900
Replied by Rolf1976_KZ900 on topic KZ200, no idle warm, hard to start warm.
Hello Lasse i guess you are from Norway to. Are you sure you have the right sparkplug i think it should be b8es wich is a hotter plug.
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20 May 2024 14:22 #899398 by Warren3200gt
Replied by Warren3200gt on topic KZ200, no idle warm, hard to start warm.
B9ES Possibly a too cool plug.
Try a set of B7ES. They will run a little hotter and keep the electrodes cleaner which will allow a cleaner spark which is required at lower revs. . 
Just make sure you don't have resistors in plug caps and resistor plugs (BR((resistor)) 7ES). Only one resistor at most in any one ignition line. 
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Z1000J2 somewhat modified!
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  • Scirocco
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20 May 2024 15:39 - 20 May 2024 15:41 #899410 by Scirocco
Replied by Scirocco on topic KZ200, no idle warm, hard to start warm.
The compression of 7 bar is a way to low, check the valve clearence!


 
 
 
 
 
My 1975 Z 1 B 900 Project

www.kzrider.com/forum/11-projects/605133...ears-deep-sleep-mode
  • K(Z)-200_specs_03.jpg
  • K(Z)-200_specs_02.jpg
  • K(Z)-200_specs_01.jpg
  • K(Z)-200_specs_04.jpg
  • K(Z)-200_specs_05.jpg
    • Last edit: 20 May 2024 15:41 by Scirocco.
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    21 May 2024 00:34 #899439 by LasseT
    Replied by LasseT on topic KZ200, no idle warm, hard to start warm.
    @ Rolf1976_KZ900
    hi Rolf, I'm from Sweden.

    @ Warren3200gt
    I think I just looked at what spark plug was in the engine when I bought a new one, in my doc it says B7ES.
    I'll buy a B7ES and check what happens

    @ Scirocco
    ok, I'll check the valve clearence, but wouldn't you here if the clearence is to small (valves not closing) when you pull of the gas handle?
    I guess it could also be piston rings, but it doesn't smoke black.


     

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    21 May 2024 00:48 #899440 by Wookie58
    Replied by Wookie58 on topic KZ200, no idle warm, hard to start warm.

    @ Rolf1976_KZ900
    hi Rolf, I'm from Sweden.

    @ Warren3200gt
    I think I just looked at what spark plug was in the engine when I bought a new one, in my doc it says B7ES.
    I'll buy a B7ES and check what happens

    @ Scirocco
    ok, I'll check the valve clearence, but wouldn't you here if the clearence is to small (valves not closing) when you pull of the gas handle?
    I guess it could also be piston rings, but it doesn't smoke black.



     
    You wouldn't necessarily "hear" anything but the valves would be closed for less time so the motor can't build pressure (same as long duration performance cams lower static compression for the same reason)
     
    1982 KZ1000 Ltd
    www.kzrider.com/forum/11-projects/617631...-82-begins?start=192
    kzrider.com/filebase-alias?view=download...d-fault-diagnosis&ca
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    21 May 2024 07:20 #899444 by Nessism
    Replied by Nessism on topic KZ200, no idle warm, hard to start warm.
    Hard to start when warm is a classic example of poor compression, commonly caused by overly tight valves.  

    First things first: DO ALL maintenance.  Waiting for the bike to fail before doing maintenance, can cause damage.
    Ed
    Carb O-ring Kits : www.kzrider.com/forum/3-carburetor/61807...-o-ring-kits?start=0
    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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    21 May 2024 09:06 #899457 by LasseT
    Replied by LasseT on topic KZ200, no idle warm, hard to start warm.
    I've checked the valve clearance and it is between limits.
    Oil level a little low but between marks.

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    21 May 2024 09:20 - 21 May 2024 09:23 #899459 by Wookie58
    Replied by Wookie58 on topic KZ200, no idle warm, hard to start warm.
    Try a squirt of oil in the plug hole and redo the compression test when hot (only a little squirt) are you checking compression with a wide open throttle ?
    1982 KZ1000 Ltd
    www.kzrider.com/forum/11-projects/617631...-82-begins?start=192
    kzrider.com/filebase-alias?view=download...d-fault-diagnosis&ca
    Last edit: 21 May 2024 09:23 by Wookie58.
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    21 May 2024 11:54 #899464 by LasseT
    Replied by LasseT on topic KZ200, no idle warm, hard to start warm.
    I did a new test.
    Cold engine, open throttle 10bar
    Warm engine, open throttle 10,5bar

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