The WT325A does not have a H needle on it, so it's not an option if you're after WOT adjustment. That's what I just took off this saw. It runs a hair richer than the original Zama which had no L adjustment either. I ran the WT325A with my muffler mod. I'm planning on porting this saw, thus my quest for a fully adjustable carb.
I just came from the garage where I removed the Intellicarb cover and reinstalled the original flat cover. I plugged the hole in the filter housing with a rubber plug. With the Intellicarb cover, I had the L needle at 1 3/4 turns out to get good throttle response. I'm now at a more reasonable 1 1/4 turns and have good control over the idle speed and excellent throttle response. I've yet to cut wood with it, but initial results are promissing.
I measured the bores of the three carbs. The original Zama is actually the largest at 0.631". Both Walbros, WT325A & WT215, have a 0.627" bore. So it's not from having too little velocity due to a larger bore. I'm guessing the Walbro just doesn't like the Intellicarb cover since it didn't come with one. I'm only guessing.
Pes+, thanks for the tip. It looks like it worked. More testing to follow once I get it in some wood again.