Very glad to be of help. You're doing a fine job, made more difficult by having to source parts from overseas. I admire your perseverance.
Make sure there is a very small amount of clearance between the teeth of the inlet cam and the idler gear. If there is no movement, you need to investigate further.
Powodzenia.

Correction. For Base Plate, substitute Cam.

For clarification, when you turn the cam by hand, it will only turn one way against the springs. That is advancing the timing.

Very easy to get a muddled head. Happens to me all the time.
I wonder if the following might be helpful?
Viewed from the timing side, the engine rotates clockwise.
As far as I can see, the cam rotates anticlockwise.
So, moving the base plate clockwise will advance the ignition.
Moving the plate anticlockwise retards the ignition.
When everything is tightened up, you can easily confirm this is correct by trying to rotate the base plate anticlockwise, but it will not move. If you rotate the plate clockwise, it will move against the action of the return springs, i.e advancing the ignition.
Always rotate the engine clockwise when moving up to the timing mark.
If you use a wedge to keep the points advanced, don't forget to remove it after you have set the ignition.
If you find that you need to advance the timing from the original position, this may make the kick back even worse, and we will have to have a rethink.
Finally, bearing in mind you will be trying to start the engine on full retard (and this is when it kicks back), it might be worth checking where the timing is on full retard. It might give us a pointer. Or, indeed, is  the timing advancing when kick starting, perhaps due to worn springs. Just a thought.

Good man. You say screws 1 1/2 turns out. This is only a starting point. They should be quite sensitive to turning. Set each one to highest tickover speed and then reduce throttle screws as required. Apologies if you already know this, but I obviously don't know how much experience you have.
It's well worth checking the float heights. Bushman tells you how.
Assuming the slide is not worn, spray oil onto the flanges and spray grease onto the inlet valves, to check for air leaks.
If you are able to get it to tick over, place a hand behind each exhaust to be sure they're even.
Does your carb have removable pilot jets?

It might be worth searching the internet for "Bushmans Carb Tuning Secrets".
This will show you the idle passages, which may be blocked? After blowing out, I spray WD40 into them so I can see they are actually clear.

Aha! I see the image is there.
This is how I did it.
Click "Drag files here"
Picture file comes up.
Right click on selected picture.
Click "Open".
Picture appears in another window.
Right click on window.
Select "Resize" and use bar to decrease size.
Click " Save".
I think you have to rename this picture, otherwise it will over write your or1ginal.
Go back to picture file, locate renamed picture.
 Double click on image and picture will appear in Reply.
I'm now going to try it again.....
Thanks Dave. I appreciate your help.
 

Dave,
You ask if this is what is on my screen, but there is no image in your reply.
However, if this reply has an image on it, I've cracked it.

Yes, I do now, but didn't before. Don't know why that is.
When I click on it now, it comes up with my pictures file folder, and I can click and drag pictures from there. However, in this folder, there is no option to reduce the file size, as there is with my other method (which won't drag the image to the reply box). Please bear in mind that I am a simpleton.

I agree with you. Either timing or mixture.
I think I would check the ignition timing, just to eliminate that. Is the A/R mechanism stuck on full advance?
You can check for air leaks by spraying some oil around the flange with the engine running, similarly with the inlet valve guide with spray grease.
Perhaps you could set your idle mixture a little on the rich side or give the carburettor a bit more of a tickle?
You might want to try a slightly richer slide. Finally, but unlikely, but you may want to try raising the jet needle by one notch. Who knows?
In the meantime, I would only try to start it using the valve lifter to ease it over compression.
Let us know how you get on.

Dave, Maybe we have different systems?
I am using Windows 11 on a Dell Laptop.
I can reduce the size of an image, but when I drag it to the Reply box, there is no text "Click or drag......".
When I release the button, the image appears full screen. So if I then remove the image by clicking the red X, the image disappears as does the Forum. All very frustrating.

I don't know if this will be of much use, but the felt seal 24-715 is shown on page 45 of the 1930 Parts Book.
I don't know of a supplier of these, but I think they are quite hard felt, and are cone shaped on one side to fit into the timing cover bush. You could work out the OD and ID by measuring the bush and quill. Maybe you could fit the timing cover with some plasticine to check the thickness?
However, for the last 30 years, I have been using Scholl Felt Corn Pads. They are about 7/8" OD. Unfortunately, since then, Scholl have redesigned them and they are now made of foam. But if you search the internet, you should be able to find some Felt corn pads. They are quite soft and a bit thin, so I use two, and have never had a problem.
Otherwise, you could simply cut one out of felt sheet. You will find the felt will easily take the shape of the bush.

I agree with Dave. It's possible they were manufactured overseas? I notice modern Triumphs all have blue pipes.
Blueing can be removed with "Blue Away" from FART. It's a bit expensive for a tiny bottle, but it does work. Unfortunately after a lot of use, it wears away the chrome. Stainless steel pipes turn a golden colour.
Last Century, I recall reading a 'Guinea Tip' in one of the magazines, that suggested wrapping 3 of 4 turns of stout copper wire around the pipes close to the head. Mine have never blued, but I don't know if that's the reason. Might be worth a try. Who knows? 

I'm with Dean on this. It seems to me that you need an advanced degree in computer engineering to post a picture, but then I know nothing about computers.
It is easy to add a picture on gmail, a couple of clicks and it's done. Why is it so difficult here?
I once managed to drag an image from my gallery, but it appeared in what seemed to be a separate reply, with a + and - symbol and some text.
None of the previously made suggestions or the help page work for me. I have managed to resize an image, but can't move it to the forum.
Surely there should just be a box 'Add Image' to click on?

The brass tap is usually used on much earlier bikes. I find they seize up after a short period of time and start leaking. Attempts to lap in the tapers are usually only a short term fix.
I can recommend the Wassell 73084 tap. Although rather expensive and flimsy, they don't leak or seize up.
Being of overseas manufacture, they have a metric sized hexagon, which is rather annoying, but the threads are BSP. It means that you will have to carry an open ended metric spanner in your tool roll, should you ever feel the need to remove the tap at the roadside. If you are a bodger, I suppose you could use molegrips.
Make sure you get either 1/8 or 1/4 BSP to fit your tank.

Further to my previous post, as far as I can gather, the actual Blue Star range was not introduced by BSA until 1932, which would make your model a 3.49 HP L31-6 OHV De-Luxe, which was not called a Blue Star by BSA. I suppose it would depend on the Engine and Frame numbers. I wonder what year and model it really is, because as I suggested, the 1931 350 would have left the Factory with the brake pedal on the right, and a hand change 3 speed gearbox.