When I mentioned jet size, I didn't realise you were at 5k feet.
150m = about 500 feet. I'm at 1700 ft and had to run 120s and the clip at the fourth position on the needle when I still had the stock airbox and 4 into 1. I tried the needles at the mid position and it ran like crap in the midrange until you got to 5500-6000 rpm then would take off like a raped ape.
ok, simple test. Get the motor to 4000 rpm (or wherever it feels weak and you need to back off to get it to pick up again. Hold it there, then reach down and flip the choke up. Does it smooth out or lay down? If it runs better, its starving for gas and if it lays down the opposite is true. Much simpler than reading plugs when you are trying to decide which way to go. Don't worry about plug chops until you start getting things dialed in closer.
I grew up playing with RC two-stroke stuff and Dad always told me "an engine will live forever a little rich, but they'll only live five minutes too lean"
