KZ1100 erratic running at 20+ mins

I had another thread on engine temperatures and this thread moves on from there.

My thermometer arrived and - no its not running hot (145 deg C at exhaust header) and cool everywhere else according to this lovely temp chart found on KZR see - kzrider.com/forum/2-engine/459413-kz1000-running-way-too-hot (halfway down thread)

Just feels b... hot as its the first big bore air cooled bike I've owned. Every other one has been modern water cooler sports or similar like CBR1000RR or Monster 600 etc.

So now its not hot - Im now back to original issue that started all this - which is after I have ridden for more that 20 mins - engine starts to blat blat out the pipe as I ride along at normal speeds (70 - 100 kms/hr) and more and more wjen braking/slowing - none of which happens when first running and cool (but now we know temp isn't the issue).

Ive replaced the pulsing coils, the coils, the igniter. New plugs.

All thats left is the carbs - but I set the butterflies by hand with carbs off the bike using physical spacer and checked the plugs for rich/lean colour and adjusted where needed. Now what?

ALL ideas welcome tks.

Tks

Valves adjusted? Pic of plugs?
Steve

Funny you say picture of plugs - just this afternoon I decided to pull them out and re check since I realised I had the carbs out a week before and - yes 123 too lean and 4 too rich so adjusted and took for 15 mile ride and it went really well I will ride now for a few weeks and re check the plugs again and see how we go.

I also replaced the fully synthetic oil I "thought" was a good idea with full mineral oil today and that seemed to change the feel of the engine and the leak stopped that started with it. All a big learning curve as I've only had modern bikes up until now.

Do you know of a good article /video on adjusting valves - so I can learn about it?

Tks

If not already done, would perform the clear-tube test on carb #4 to assure that the fuel level is within spec.

A too high fuel level may be expected to result in an excessively rich air/fuel mixture that's difficult if not impossible to otherwise adjust, and which can produce the reported symptoms.

Good Fortune!

Valves hanging open once hot would be my guess. Hopefully there is not permanent damage. Valve adjustment is one of the critical maintenance items, and one of the most neglected.

After reading text Im not clear on one item
You say you pulled carbs and bench adjusted them .
Did you synchronize all 4 with motor running ??
Were carbs rebuilt to insure all fuel and air passages clear ??
Are you running a fuel filter ??
Along with valve adjustments these are all part of a good tuneup
Dave