I mowed again last weekend without changing anything, but today I did mess around a little bit with the carb. I swapped out the 901 e-tube that was in there for an 841, and followed it up with the 65 main jet I had. It already had a 60 main jet, so not much of a change there. Wish I had picked up an 80 main jet before playing with it, but oh well. Pretty much just changed the 901 e-tube for an 841, considering how small of a change one step is with main jets. It is probably best to only change one thing at a time, anyways.
She fired right up when I put her back together... which is good. I tied the pull cord around the handle and let her warm up, then turned the fuel off to run the carb dry. Didn't really notice anything different. I need to get the proper tools to measure what, if any, changes are actually happening.
If my understanding is correct, the 841 should switch from the idle circuit to the main circuit quicker, in juxtapose to the 901 that was in there. The porting arrangement on the 841 suggests I have made low rpms richer and high rpms leaner compared to the 901 that was in there... which is actually the opposite direction I want to be going. We will see if she seems starved for fuel up top/at full load next time I mow.
I am willing to swap out e-tubes between each time I mow, in the name of science. It is a pretty simple operation. I haven't messed with the governor, yet, either. Once she was all warmed up, I flexed the governor with my finger to see if she ran better or worse one way or another, but didn't bend the governor any to permenantly change anything. She seemed to run about the same as much as I was willing to flex the governor in both directions, so I might actually have enough fuel available to turn her up a little. Need to see if she leans out too much up top/under load before I go turning her up at all, though.
And I completely forgot to take the bolt-cutters to the limiter tab on my idle mixture screw... need to do that need time I have it apart anyways. So any excuse to take her apart again will be an opportunity to make the idle screw adjustable.