Advancer maybe?

Alright here we go - Kaw 440 Ltd, I have checked...
Timing
Valve clearance
carb clean
jets clean
new seals
Carb boots no holes, no suction when doing the spray test
voltage on the battery - high beam test

Right at the 4000 mark it will fall, I hold the throttle right at 4000 and it falls apart, hold it there for a few seconds then start slowly reving it up. At some random point it jumps up above 4000 and takes off but sounds like a pile of crap.

Help?

Have you checked if the sliders of both carbs are moving sync if you pull the throttle.
A leaking diaphragm#58 or a missing plug#50 can be the problem.

It sounds like you have some kind of blockage in one or both of the fuel paths above 4,000 rpm. I would check the needles to see if they are set in the correct slot. Take a look to make sure the needle jets are clean. Would also check the main jet diffusers to ensure they are clean. You should also check your float levels.

Holy crap you nailed it, I checked both these before but never caught the tear, good call.

And what does the plug look like I think I am missing it in both carbs?

Also, replacements, is there a go-to for all things 440?

Thank you again!!

The plug and the o-ring:

www.cmsnl.com/kawasaki-kz440d5-ltd-1983-...121128/#.Xcx_6bmWw_w

$55 for a set of o-rings and plugs?!

Awesome.....

Anyone have a set they want to sell for something reasonable?

Buy now !
Those plugs are really rare.

I have never ever seen them for sale

An alternative plug solution, made your own:

kzrider.com/forum/3-carburetor/602978-kz...arb-questions#732099

Diaphram and plug replaced on both sides. Still failing at the same point. Back to advancer?

Nothing to lose by checking the advancer but I think full advance is at about 3500 rpm so by the time your issue occurs at 4,000 rpm the advancer has done it job ? You can check that it is not seized and if necessary invest in a timing light and test as per the manual

If your issue occurred at 3,000 rpm then I would suggest looking at the pilot bypass circuit in your Keihin carbs but then I'm not familiar with the 440. Still , if you have the carbs off again then perhaps worth a look ?

A group of 3 tiny holes just behind the throttle butterfly. Very easy to miss when carb cleaning. A small fine pin with the tip bent at 90 degrees will work - be gentle.


Hardrockminer makes an excellent suggestion to check fuel paths for >4,000 rpm which I think in your case would be the primary and secondary jets. Your 440 manual has an excellent section on the carbs starting on page 148

Also take the bowl off and remove the pilot plug and wearing eye protection - very important - block #6 with a finger,spray carb cleaner in #4 and watch (eye protect) for it to exit at #3.




One last thing.
You say the carbs were cleaned but were the float bowl fuel levels set using the clear tube method ? If not then this wont be the cause of the issue at 4,000 rpm but an imbalance might cause "takes off but sounds like crap over 4,000"

Anyone have dimensions of the plug?
What is it made of?
I think I could machine few cheaper

No eBay APP ID and/or Cert ID defined in Kunena configurationThose polyester caps seem like a good candidate for 3-D printing.
Here's some aluminum plugs. for reference >> Kawasaki part number = 11012-1128

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