Decomp is lapped and I’ve hit it with carb clean many times but may try the air compressor test too, apparently if you take a spray nozzle for an air compressor and spray around the engine while it idles that’s even better than carb clean. I though 21 seemed like a lot too, everyone else seems to be around 15-18. Like I said maybe my carb was a bit wonky last time I tried less. 3g sliders were about 18 g total sometimes 19g my scale is not the best I just was told make sure you weigh them all at the same time.
I’m running a b5hs which apparently sucks at dissipating heat I’ve read. Was reading some other two stroke forums tonight and was reading about how bikes that run WOT a lot of the time do best with cooler plugs like a b8hs because they dissipate heat better to the head. Something with the length of the electrode being different. Also thinking about the Parma box, seems they run fantastic in derbis with their wicked top end curve