FYI, 180 main jet in a keihin carb 1.8mm diameter and that will flow 4 x as much fuel as a #90. Or did it have a minkuni jet in that carb?Go on line or contact your dealer and see if you can get two good new Keihin main jets for that carb. Early and late Honda's use different threads - same diameter but different pitch. I can't remember which pitch the 175 used and what that is compatible with but can check it over the weekend if you need.
Cool. One thing I try to do now is to set FUEL level and not FLOAT level. That way, any float problems are obvious and it's what we are actually trying to do when we set the float level. Doing it "wet" where possible is more accurate.
Get a drill bit that's just a hair bigger than the 6mm bolt shaft, and drill through the head of the screws until they pop off. Take the cover off, and I'll bet the rest of the screw will come out by hand. If not, vice grips. Sent from my iPhone using DO THE TON