Atv 50cc

i have a 50cc e-ton 2 stroke atv that i got for free from somone?

i got it to run but it dosent go past 3/4 throttle it dies out like its not getin gas but i cheacked everything and it is getin gas but it goes good i weigh 145 and it goes 16/17mph with me but it has black oil that comes from the exhaust and the front of the engine is this normal for 2 strokes?
i need to know asap

Check the throttle assembly for a screw that limits the travel. It acts as a governor for when little kids ride them.
The oil is usual, the fuel/oil is probably wrong (too much oil).As long as it doesn’t foul the plug, don’t worry too much.It can’t hurt anything

Bjorn driving ATV 50cc