We all have had our ass handed to us out there buddy... Hell I, as a new TW student, ground looped twice in one day! (No better way to learn than THAT!!) Thanks for posting. This is a great reminder for everybody to review and think through.
Chart above is from CPS for the 912uls. Pretty flat curve! Looks like adding 400 static rpm would only add about 5 HP. But enough paper speculation!! Fly it and time a few runs from brake release to say 500 or 1000 agl. Then pitch for 5300 and see what the difference is in time to climb and also see if you notice better off the ground performance. In my O300 Maule (yeah I know, apples and oranges, but) I made a 300 rpm pitch increase and it was VERY noticeable!
The power curve of that motor would show if you would get better TO perf with more static rpm. Likely the engine will produce more HP (and thrust) at a higher static rpm. Problem obviously is the revs might be higher than you want in cruise when you set for optimal power during TO. My plan is to do some static thrust pulls at different pitch settings and get an idea of where my prop-engine combo will work best (also considering that rpm "ram" rise during the TO roll and in cruise) With a fixed pitch prop it obviously will end up being a comprise to a cetain degree
Easiest way is the "water trick". Essentially you fill the clutch bolt hole with water, then find another bolt that has threads that match the larger threads in the center of the clutch (get a flashlight and you'll see them), wrap teflon tape on those threads, and thread it in.... the hydro pressure forces off clutch. Here is a vid of one way to do it using a bolt from the sled. I would weld the hole on the end of the bolt closed if I used that bolt, wrap teflon, tip engine up, fill water, thread bolt in, pressurize water... off comes clutch. (And no that's not me in the video... I'm a hell of a lot uglier than that)
Wonder if that is a mechanical fuel injection? Kinda like my subaru which it is basically like a garden hose sprayer nozzle: as you push the throttle body plate open it also opens the fuel sprayer nozzle. That as opposed to a digital efi where it controls injectors via a computer, automatically adjusting for engine temp, air temp, and pressure alt, ect. The mechanical FI doesn't seem like too much of an advantage over carbs... except that you can incorporate a lean/rich mixture lever in there where it offsets the fuel nozzle position with respect to the throttle body as they move together. I really dont know much about it. Hopefully someone here who has tried it might chime in. But seems like tuning for all the carb ranges might be difficult (rich at a certain rpm, lean at another..) maybe more workable on a 4 stroke where a little lean here or there isn't as big of a deal.
Dang, no not able to make it to Anoka... but hopefully you can swing up north sometime and put another set of eyes on my work! Also, Matt Plante (Yam FB group) over in Stacy is halfway done with his Wild West Highlander. His FWF Apex is coming from Steve sometime later this year. So if you're looking to see how to do a Yamaha the right way, that'd be the one to look at!