Carb flat spot

After having the monobloc of my Model 50 sleeved, I tried setting it up correctly and seem to have done it nearly right.

I've been treated with a bike that actually idles when I stop at traffic lights and doesn't even change revs (as much as it did) when I park it on its sidestand. It starts perfectly too and behaves like it should. When pulling away, there's no hick-up when opening the throttle, just a direct response. Weird, isn't it?

So, that's all I wanted to say really...

Of course it's not. Nobody bothers posting here when not in need of advice. And I could definitely use some.

It's all as good as said above, but when I pull away, there's a barely noticeable flat spot, just about where the throttle is 1/8 of the way up. It doesn't stutter, it doesn't fall dead, it just seems to do nothing at that throttle opening. It doesn't take much pulling it through, just a fraction of throttle. In fact, many might not even notice.

Still, I've never dreamt of it running so smoothly and I'd like to get this last bit sorted too to make it perfect. It's definitely rideable and it doesn't really irritate me. I just want to see if I can get it perfect, since I've come so far.

If anyone's wondering; I've left out jet sizes on purpose. That's because I do really want to get some insight in the workings. The how and why, so to say. And as it's old stuff, you can never be sure they've not been reamed. So mentioning numbers could theoretically mess up advice.

I'd really appreciate any thoughts on this matter.

Cheers!

Tim