Breaking in an engine really does have a lot of different views but the biggest factor is if you're the one paying for the engine then it's best to honor what the manufacturer says. That said, I'd treat engines by their value meaning I'd not have as much worry over a motorized bike as like a Harley or expensive car. That said, most the bike engines I've seen(I'm no expert) are basically junk from the manufacturer but that might even be more of a reason to go easy on the break-in unless you're able to tear down & repair an engine. I'm not so I'd treat an engine w/ kid gloves but if I had the tools/ability to tear down the engines I'd ride the piss outta my motorized bike & replace parts. I still have not found an engine for bikes that I trust which means I'll have to find a man like you to help me build a worthy motor. I'd never buy a bike berry motor but I'm still looking at motors/engines for a decent one. peace