Sorry for a slightly longer post, but here goes. I had pod filters on mine, the kind that don't block the air jets, so had increased the main jets to 150, then 155; it ran OK, but still had issues over parts of the rpm range. When the OEM style replacements showed up, I grabbed a set, and a pair of jet kits that include a selection of mains and needles to match, new needle jets and pilot jets; didn't use the pilot jets, but did the needle jets, just in case they were worn. I dropped the mains to 149 with the matching needles, and it was still hard to start, enough that I used one of those booster batteries on 'cooler' mornings (<80F). After a tankful, I pulled the plugs, and both were covered with soot. So I put in the stock size 145 mains and matching needles from the kit; it started right up, and the plugs are getting clean! Bottom line: too rich will make this engine harder to start, too. I haven't needed the booster battery since; of course, it's been rather warm, which helps, too.
To set the floats, I use a float gauge I made from a bit of sheet aluminum, from the photo in the manual, and hold the floats up with it, then turn the petcock on. If the fuel just weeps past the float valve, I'm happy with the adjustment. Any more than just wetting the valve, and I adjust it; no wetting, and I ease the gauge down to see how far it takes to get fuel to flow, and adjust if it's more than a few hairs.