Def do a leakdown test. 400 mains is huge for that motor. I was spot on with 340 main 27.5 pilot 1.5 air screw mid clip stock needle in warm weather (60+) with stock carbs, since your a bigger dude IMO I would of went with a bigger motor like a 4 mil serval Ect but work with what you have for now. Get the jetting spot on first and then try it out again and report back. If it's still doing that could possibly be a dome issue when jetting is dialed in