i've never had any problems breaking in with 50:1 but i usually mix a little heavy for the first few tanks.
i also use premium gas for break in because its more forgiving if you have any tuning mistakes. it resists detonation until you get your settings dialed in.
my biggest thing with break in is just forcing myself to take it easy until things are dialed in... i built a bike last spring that felt like it was running good and about 20 minutes after the first start i whanged it up to like 12k rpm and broke a needle bearing roller... dumb dumb dumb..... it was a bad china bearing from the get-go but i probably would have been fine if i hadn't just jumped on it right out the gate and blued it up.
when you're still trying to dial things in just force yourself not to run it too hard and you'll have more of a chance to make sure everything is perfecto before you start beating the piss outta it.
also, the one thing i've found with break-in on V1's is that it helps a lot to gear them up, even more than you plan on finally running. Keep that load on them because its way too easy to over-rev them with stock gears.