Turn up the pump, hand cut the fuel cone, advance the timing unto it wraps up smooth when warm from idle in neutral (as in floor it in neutral). If it pops then back it off a little.
HX40 impeller upgrade through Gillett to 60mm, 16CM exhaust housings are cheap and work awesome with the 60mm. I run POD injectors because they were cheap. Been running them for a long time, just with the thinnest copper washers to get the tip down in the bowl as far as possible. I would go with a piston lift pump also, add a fuel filter back by the tank. Straight pipe of course. 3,200 RPM spring. I had to use a billet tappet cover with additional crank case vents because I kept blowing oil past the stamped one.
I now have a 62mm impeller and the 16CM is a little too big to drive this impeller at low RPM, gotta whale on it but it screams to high RPM.
Need a 14CM