leo, you're doing 35 mph on a motor with 50 mi on it? That's not what most people around here would call 'broken in'. Usually that's 2-3 full tanks of gas/oil.
These China Girl motors are proven to give good results, but you've got to break em in before you work the bejezus out of em.
Your chain isn't even stretched yet (it doesn't, but the rollers and pins wear, and your drive sprocket wears). That's at about 100 miles.
If you feel it's ok, then go for it, some of em are quite good right from the start. Would just hate to see you lose it before you get some riding out of it.
Hey, I just thought of this as well, it's something every new 2-stroke owner should read. It's involved, but worth it;