Worn Needle Jets

I am running a single VM34 on my '73 850. I've been dealing with a rich condition from idle to 1/2 throttle. I was using a 27.5 pilot, 2 turns out AMS, and 3.0 slide. The plugs were sooty on the base ring, almost wet. Low 30's for mileage. It was rich not matter what. I remembered someone saying that they replaced their needles and jets when they were up against carb puzzles like this. I think it was Rick in Seattle. So I did it.

I left the 27.5 pilot in and it wouldn't run when I shut the choke off till I closed the AMS down to 1/2 turn out. I replaced the pilot with a 35 and set the screw at 1.5 turns out. It's crisp, nice response to small throttle openings. Plugs are still dark around the base ring but cleaner and I get 45mpg. It must have been pouring gas by the worn jet, from idle on up to getting on the taper.
I'm using a 250 main. I don't get a surge backing off slightly from WOT. Bushman recommends 260. Anybody running 230-240? Thanks.

I have run all the way up to 330 with out richness issues on my 750 when I had the vm36. I do not think it is a main issue.
What is your needle and needle jet numbers. Have you tried lowering the needle (raising the clip)?

6DH3
159P-2
35 pilot
3.0 slide
250 main

I'm more or less happy with the way things turned out for idle up to about 1/2 throttle. I'm probably not right on the money yet, but compared to what I had going on, it's like night and day. I can't make any distinction from looking at the plugs anymore except for "not even close" jetting. I don't think the main jet is in play on lower throttle opening either. I just want to see, now that the low to mid throttle opening jetting is ok if there's anything to be gained by looking at the main.

Up near WOT it doesn't actually crap out so much as it makes no difference if I continue to open the throttle from 3/4 to WOT or not. I was thinking about dropping one size at a time on the main till I get the surge when you go from WOT down to 7/8th's. Then take it up one or two sizes. That way I'd know in close without having to base it on reading plugs.

Somebody mentioned a couple days ago that it could just be the limits of a single 34mm carb's ability to move air. You may have got it right by going up to 40mm then solve the hesitation problem with the pump. The fact that it's a flat slide might also be helping with eliminating the hesitation too.

The move to a 35 from a 27.5 was in the right direction. I recall using a 40. Sounds like you are close even though you are probably at the limits of that vm34 with an 850. Try a #40 pilot.