Re: Intermittent 4 stroking
Drop a jet size and raise the needle back up. When it pulls up to top then four strokes, the jet is too big. The needle is fully out at this point so your jet is the controlling factor.
Remember to raise the needle back up when you swap to a smaller main and approach peak power carefully.
I like my engines tuned to pull hard up to the redline and four stroke just a bit at partial throttle cruising speeds.
And some four stroking is simply the nature of the bbeast with these motors, so don't worry about it too much. You will know when it's too far, jetting it just under max power is a good idea for engine life.
If more is better, then too much is just enough.
If you can't afford it, build it yourself.