It may be a bit awkward, but for the first start of the season, I squirt a little gas straight into the muffler while the bird is on the assembly stand and upside down. I then angle the aircraft in such a way as to guide the gas into the exhaust outlet. Make sure the piston is somewhere near BDC and following that, rotate the prop to close off the exhaust port, then set the bird back on its gear. Works EVERY time and doesn't require any rebuilding, etc. I suspect the idea comes from my old .049 days. Nothing better than a direct exhaust prime.