81 GPz Running like complete crap. Ideas?

1981 GPz550. Stock. 17k miles. Has not run great in years. Assumed dirty carbs but cleaned the carbs and ... no real joy.

Compression high 140s to 150 all the way across
Stock carbs are clean.
Fresh and tested well battery
Checked connections to coils, replaced coils with set from running 550,
New plugs, new plug caps. No difference.
Fresh fuel.
After this it no longer needed starting fluid to start. but ...

AND STILL RUNS LIKE CRAP
# 1 cylinder runs cold--like almost put your hand on the exhaust pipe. All others seem hot.
Fouls plugs all the way across at times, #1 most common.
Tried to take it out for a ride but revs were hanging at 3-4 k then it started to die and I limped it home.

PULLED THE CARBS
Expected to find clogged pilots and the rest but they were shockingly clean--could see light thru the pilots.

I'm stumped.
Any thoughts or advice welcome.

Does the motorcycle have the stock airbox with good air filter or does it have the individual pod type filters?
Also, are the mufflers stock or does your 550 have a 4-1 exhaust system?

Stock box, new Kawi filter.

100% original exhaust.

Someone said to check the timing. Is this possible to do on an 1981 model with the non-points equip, do you know?

Check valve adjustments. pics of plugs? Old valve guide seals can foul the plugs.
Steve

Are you sure the wiring is correct and spark plug wires are routed to the correct cylinders?
Do not avoid checking the valve clearance? It isn't that hard. fairly easy. Adjusting them is the harder part.
The Kawasaki electronic ignition is fairly reliable and non-adjustable. You can check the timing with a strobe light to make sure it's advancing properly. Advance probably begins around 1400 rpms and full advance is probably above 3400 rpms. see the Ign system info in the manual.
What you should do is to clean, check and lubricate the timing advancer. Separate the rotor from the advancer body & fill the groove with grease. Make sure the springs aren't stretched or damaged. You should also examine the pulsing coils & plate. Common sense type of things. Look for rust or corrosion and make sure the pickups aren't cracked, melted or damaged. Also, there should be 3 screws, fastening the plate securely to the engine. Using a 17mm wrench, turn the crankshaft to make sure the advancer doesn't contact the pickups.
(warning: don't turn the crankshaft by turning the smaller advancer bolt 14mm).

Cracked carb boots? I don't see any mention of replacing them. In my experience even very good looking ones can have leaks.

Brand new Kawasaki carb boots.

Since #1 is problematic, I would focus on everything related to that cylinder.

I agree, the fact that #1 is different from the others means you should start there and find out why.

Have you removed the emissions air suction system? Make sure that is not leaking air into the intake amnifolds, They should all be capped off, as well as the valve cover ports being capped off.

The compression is very low at 140 to 150. I've never even seen a worn out motor that low on a Kz550. The Gpz 550's all end up between 175 and 190, even with a 35 year old motor run regularly.

I suspect it's your gauge or testing procedure. If not, then the motor needs to be looked at closer. Maybe a leakdown test first.
(If you do a search for compression gauges, there was a time when China was making gauges incorrectly and they would not pump up properly. You might have one of those gauges. I regularly use several different old-school gauges to confirm the numbers, and they are always within a psi or two of each other. ) I then use a new chinese defective gauge and it will be 50 psi lower.

Look in my signature to download several service manuals and a website for the Tk22 carbs on your bike.

The hanging idle is symptomatic of a vacuum leak or a severe sync problem. If you've had the carb tops off and removed the slides, you need to closely examine the slide positions and installations. This has come up on KZR before.

Also , are you using rebuild kit parts? Look on the Tk22 website for details on problematic counterfeit rebuild kit parts.

Lastly, have you checked the choke flap condition? There are details for that on the website as well, and will show what to look for. That will greatly affect startup.