Hi Juan, The harder starting hot is normal with California fuel. I know you have the proper fat o-ring insulator between carb & manifold. That is important, but still it doesn't cure this problem. (the phenolic insulator block won't help more, trust me).
The solution to the hot start like you experience is two things. First don't use any throttle at all during first 10 min until bike fires, then add throttle & blip throttle to keep it reving until carb cools & it will idle normal. About 2 min or more depending on temperature.
The next thing sounds wrong & crazy.... But it's the only way that actually works. Tickle carb like when cold. No choke. Bring to compression. Turn on key. Hold almost full throttle (about 90-95% full). Kick very hard. Be ready to back off throttle as motor will race quickly. Again blip throttle until it will idle reliably, about 2 min. Don't do primer kick when hot like you might when cold.
If still no good, kick with zero throttle.
There is a bit of a knack to this, but once you get it, bike will start 99.9% of the time hot on first kick. All the guys I ride with do this & it works for everybody.
On a side note, many riders find they can kick harder & turn motor faster if they clock kicker lever to near horizontal. Do this by first freeing clutch. Then bring to compression. Raise lever, pull clutch, push lever part way down to near horizontal. Hold it there. Release clutch still holding lever there. Don't raise lever, keep it there. Now kick hard. This really works well. Many of us do this. Takes some practice, but soon is second nature. Even small light riders like me can reliably start bike like this.
I would most strongly recommend you don't move needle clip until you evaluate mixture by road testing with the tuning guide in your pocket. Mark your grip in 1/8s like a ruler with long & short lines using masking tape on grip & chrome part of throttle so you can see at a glance exactly how much throttle you are using at the moment. This marking is most critical & important. You cannot guess on this. You must mark.
Study tuning guide. Print it all or at least the parts about tuning. It takes some time to digest all that's going on with carb. Generally takes several road tests. Your road tests are way too short to get any reliable tests on running or reading plugs. You need to go a minimum of 20 miles just to fully warm engine. More if cold day. It must be fully heat soaked to evaluate mixture in all the riding conditions.
Ride & read guide. Ride & read guide. Repeat as needed until you memorize most of it & get a feel for what parts of carb does what. Then if you want move the clip. Then you'll not be guessing, but actually understanding why & what you need to do.
Here's the guide done by John Healy. The link doesn't look right, but it is indeed the correct link to guide. https://www.princeton.edu/ssp/65-cub-data/library/amalbritbike.pdf