Cheers Anderspa,
The charcoal canister has nothing to do with the SAS - BTW it's ok to delete the charcoal canister without a dongle so long as the oem purge valve is left plugged into the harness and the vacuum hoses it uses to suck fumes into the throttle bodies are plugged off so they no longer suck air into the engine - rottweiler video covers this too.
The SAS = supplimentary air system, injects air into the exhaust pipes to fudge the emissions readings and to help the catalizer heat up quickly - most owners remove the SAS plumbing after they have removed the catalizer (de-cat mid pipe) because once the cat is gone, there is nothing for the SAS to do. I still have my SAS and cat but have long ago tossed the charcoal canister out (and the dongle I foolishly bought through innocence/ignorance fried itself on day 1, hence how I know it was never needed as my KTM tech simply plugged the original purge valve back in and said it does the same job as the dongle anyway).
Steering head bearings are just bearings and some settle faster than others with use, or as you mention, the factory torque tooling might not have set them properly, or needed a reset....... some 1290's have had clunky front ends which miraculously go quiet once the stem bearings are tensioned down again........ it's true, and your 3rd hand 1290 has probably had them checked at some stage before you acquired it

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Oh the O2 dongles - if your's has been remapped for an exhaust pipe or whatever, then it should not need the O2 sensor's removed and dongles installed - this kit richens up the under 5k rpm mapping, so the new dyno tuned map would now be running out of tune......... the O2 dongles were just a cheap fix for a stock ECU map which runs on the lean side of correct to meet emissions regs.
Best for 2021... hope you guys get that virus under control soon...... we've just had a short sharp lockdown here in Brisbane to make sure a mutant case didn't get a start, and that worked a treat, so now I think I'll go and suit up and take my 17GT out for a gallop