Like stated in post #3, why did you swap out the engine that came with the bike? I bought a brand new one 2 1/2 years ago. Put in the billet rod and flywheel, .265" lift mid duration cam, 26 lb valve springs, 60 tooth rear sprocket, air cleaner, pipe, and carb jet. I am 225 lbs. Bike runs 44 mph
and will climb ANYTHING. Sorry to hear you spent your money for nothing.
Save that engine for a future build. It's a good one.