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Help me figure out my startup knocking / clanking [Update] 09 Dec 2018 11:49 #794853

  • ERIK814
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I took apart and cleaned the carbs. I've also stopped letting the bike run at such high RPM when warming up (thanks Ed650). But I still get the clinking sound. Upon taking a very close look, I have noticed a couple more things:
1. When the bike is warming up there is a periodic release of air from the right carb boot, on the engine side. This happened before I cleaned the carbs, and continues to happen after I cleaned them.
2. It sounds like the clinking is coming from the right side of the motorcycle.

Again, once the motorcycle is warm the clinking / air ejecting stops and everything sounds fine. I would like to get this thing running like new so any ideas would be much appreciated!!

Here is another video -- the clinking happens right at the beginning of the video, and the air ejecting from the right carb boot happens around minute 1.

1981 KZ 440 LTD Belt Drive (Late Model)

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Last edit: by ERIK814. Reason: typo

Help me figure out my startup knocking / clanking [Update] 09 Dec 2018 12:42 #794859

  • Scirocco
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Looks like the enrichment or choke circuit is blocked and the engine runs under lean air/fuel conditions .
Have you check the valve clearance and float bowl high too???
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Help me figure out my startup knocking / clanking [Update] 09 Dec 2018 14:02 #794863

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I did not check the float bowl level when I pulled the carbs off -- probably should have done that. Do you know if that can be done with the carbs on the bike? It was a pain to get them back on.

I will buy a thickness gauge and test the valve clearance and see if it helps.
1981 KZ 440 LTD Belt Drive (Late Model)

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Last edit: by ERIK814.

Help me figure out my startup knocking / clanking [Update] 09 Dec 2018 14:32 #794864

  • gordone
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Much easier and accurate measure height when the carb is mounted on the engine, see attached photo.

1981 KZ650-D4, with 1981 z750L engine (Wiensco 810 big bore).

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www.kzrider.com/forum/11-projects/607213...sr-1981-z750l-engine
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Help me figure out my startup knocking / clanking [Update] 09 Dec 2018 14:42 #794865

  • Scirocco
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Do you have a service Manual for your bike???
If not get it here:

www.kzrider.com/modules/ServiceManuals/kz440.pdf

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Help me figure out my startup knocking / clanking [Update] 10 Dec 2018 05:25 #794877

  • Nessism
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The noise is not a problem, it's a symptom. The engine is misfiring. Most likely caused by carb problems but it could be ignition or even mechanical like valve adjustment. Don't know. What I do know though is that you can't troubleshoot problems on a bike that doesn't have all the maintenance up to date. Valve adjustment being just one example. You should get yourself a factory Kawasaki manual, not a Clymers or Haynes, and go through all the maintenance. When cleaning the carbs they should be fully disassembled and the hard parts soaked in carb dip. It's not a hard process, just takes some care. You can reuse all the existing brass carb jets so don't waste money on aftermarket carb kits. Source new soft rubber O-rings though.
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Help me figure out my startup knocking / clanking [Update] 10 Dec 2018 12:40 #794899

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Thanks Nessism. I will continue to do the routine maintenance - the person I bought the bike from said they had done all routine maintenance to date so I was hoping it was something minor that a person experienced with older KZ's could pin point based on sound (I know - long shot).

I used Berryman B-12 Carb Cleaner when I took apart the carbs. I fully disassembled everything, sprayed a bunch of the carb cleaner in the float bowls and let the brass soak in it for a few minutes. I then shot more of the carb cleaner through the holes, followed by compressed air. I did the light check and the holes all looked clear.
The o-rings were in good shape (the one on the plastic plug had some minor damage) so I did not replace them.

I'm super newbie to anything mechanic-related. But I have been working from the following manual. Is this not the factory manual?
www.kz400.com/Workshop%20manual%20bilder...Service%20Manual.pdf
1981 KZ 440 LTD Belt Drive (Late Model)

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Help me figure out my startup knocking / clanking [Update] 10 Dec 2018 13:31 #794901

  • FatDaddy
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You will also need to resync. the carbs.
However I don't believe the noise will be related to the carbs.

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Help me figure out my startup knocking / clanking [Update] 10 Dec 2018 13:40 #794902

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ERIK814 wrote: Thanks Nessism. I will continue to do the routine maintenance - the person I bought the bike from said they had done all routine maintenance to date so I was hoping it was something minor that a person experienced with older KZ's could pin point based on sound (I know - long shot).

I used Berryman B-12 Carb Cleaner when I took apart the carbs. I fully disassembled everything, sprayed a bunch of the carb cleaner in the float bowls and let the brass soak in it for a few minutes. I then shot more of the carb cleaner through the holes, followed by compressed air. I did the light check and the holes all looked clear.
The o-rings were in good shape (the one on the plastic plug had some minor damage) so I did not replace them.

I'm super newbie to anything mechanic-related. But I have been working from the following manual. Is this not the factory manual?
www.kz400.com/Workshop%20manual%20bilder...Service%20Manual.pdf


You've got the right manual! Good job.

It's typically advisable to soak the carb bodies in carb dip, not just using spray cleaner unless they were pretty clean to begin with. Did you remove the pilot screws and make sure the passages are open between the main jet and all the various holes? Did you hold the pilot jets and bleed pipes up to a light to make sure they are open? And what did you do about carb sync?

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Help me figure out my startup knocking / clanking [Update] 10 Dec 2018 15:02 #794904

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They did look okay to begin with, but I think they looked better after cleaning them. I did remove all of the screws and checked the passages (I sprayed cleaner through them followed by compressed air) and they appeared to be okay. I also looked through all the holes and from what I could see they were clear.

I visually inspected the butterfly valves and they seemed to look like they opened and closed together and I could not see any gaps or anything that would require a sync.
1981 KZ 440 LTD Belt Drive (Late Model)

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Help me figure out my startup knocking / clanking [Update] 12 Dec 2018 15:57 #795045

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I attempted to adjust the clearance on the valves. I had difficulty getting the thickness gauge into place without loosening the screw, so I went ahead and loosened / re-tightened all of the valves. I used the 0.20 mm gauge since the manual says the valve clearance can be between 0.17 to 0.22 mm. I tightened the screw down until I could barely slide out the gauge, then I tightened the lock nut. Now there is a TON of clanking around when I start up the motor -- like a sewing machine. I will try to set them again tonight with the 0.18 mm gauge and see if it helps. In the meantime, anyone know what the deal is with that noise??
1981 KZ 440 LTD Belt Drive (Late Model)

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Help me figure out my startup knocking / clanking [Update] 12 Dec 2018 16:08 #795047

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Have you do the valve clearance adjustment in the same TDC for both cylinder?
Have try to adjust the cam chain?

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Last edit: by Scirocco.
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