I've been testing different theories for years........ I honestly don't think break in matters. It's how you treat it afterward... but this is JUST MY OPINION. I just finished my Tecate-4 2 nights ago. Within 2 minutes of it firing up for the first time this millennium I ran it WOT through 4th 3 times (too dark to go to 6th, plus it was cold as hell)
EDIT: I forgot to add one thing.... I DO run all my 2 strokes rich during break in. Also, I do not use synthetic oil for the first few tanks of gas.
I've drove my AMR840 like I stole it. We will see how it works out. I was careful with cam break-in. Changed over to synthetic at 14 hrs. 127 miles. Don't think there are many quads that can beat me. I just raced a raptor 720 guy has 16,000 in machine and took him all motor by a quad. I took first in 1/4 mile 87 mph and 300' 60 mph at 5100 feet . Times may look slow but they are not for the elevation. With race cut plastic 93mph and without 86. Thats right 7 mph difference. Dynoed twice once at 72 second time 75 at 1500 feet. Don't think any UTES can keep up and very few sport bikes.