CV carbs work by both throttle position and RPMs so you have to take both into account. Your slides operate by vacuum. Higher RPMs create more vacuum and more slide lift. It's possible to get up to redline and get the slides pretty much fully lifted using only, say, half throttle. You would be running mostly on the mains then but if you were trying to tune by throttle position, that might have you thinking you were running on the needle (midrange circuit).
Throttle position does play a more prevalent part at lower speeds and RPMs. You're uncovering those small holes in the main bore that let the pilot circuit fuel flow in when you open the butterfly plate. I should mention here that your pilot circuit never just turns off, it's always flowing and adding some to the carb's overall flow and mix. It doesn't have a large effect when you're going really fast and turning high RPMs, but it's there. Carb manuals will tell you it effects up to 1/4 throttle. Well, it effects MOSTLY up to 1/4 throttle, but it's always there adding some fuel. I would also suggest equalizing your mix screw settings. Having them a half turn off from each other isn't good or right. On the BS34s especially, it can cause popping and a hanging idle speed (slow to return).
It's easy to over-jet CV carbs because they work on engine demand. The slide will only lift as much as the engine can use no matter how far you twist the grip open. So, the bike can seem to run OK with really big (too big) main jets because the slide isn't lifting and pulling the needle all the way out of them - they're not fully flowing.
Since CV carbs are so forgiving, to properly test your jetting, you have to push them hard. In the case of the mains and midrange to main transition, you need to run full throttle tests from about 3 to 3.5K up to near redline in 2nd, 3rd, or 4th gear. In particular, this will uncover any stumbling in the upper midrange, in the midrange to main transition area, which is an indication that your mains are too large. If you've never tested in this manner, then you'll never know. If you just putt around all the time (which it sounds like you do), the bike will run with just about any jets you put in there.
For testing the pilots, find a large parking lot and ride around in 1st about as slow as you can go smoothly. At that slowest steady speed, look for surging which would indicate you're too lean. Occasionally, grab a big handfull of throttle to test the idle circuit to midrange transition. You don't need absolute full throttle like for the main jet test, just a big handful is good enough. If you get a giant hesitation or flat spot before the bike goes, you're too lean. If you get stumbles and break-up, you're too rich. You can attempt to tune these glitches out with the mix screws but they only control about 1/4 of the fuel delivery from the pilots. They are for fine tuning and may help but may not fix the problem completely. A pilot jet size change may be called for in that case.
