Honestly no reason for despair, just an opportunity for learning.
Unless you've done damage to the engine this is a drive train issue.
These drive trains are reasonably tough and fairly simple. It's possible your friend made an innocent error in assembly..these are annoying but they happen, or something's just a bit out of whack.
Some possible causes off the top of my head...
- An improperly installed/reassembled belt replacment causing the CVT to stay further open than it should. Basically like starting your car in second gear.
- Bad rollers. This would cause things to not shift properly.
- Glazed clutch. This might be clear-able by doing the bike against something solid, front brake on and rev routine (do NOT attempt this with ANYTHING vulnerable in front of ya. DO wear gear..if the bike gets away it can get way fast)
I'd order some fresh rollers if those weren't already replaced, and take it apart then reassemble carefully, probably manually de-glaze the clutch bell and pads (a little fine sandpaper or steel wool..)
Verify the pads have some meat on 'em, & reassemble paying careful mind to how it goes together.
I'd offer to help, but you're a long way from Seattle.
If there's something I can help you with remotely lemme know. I've done that entire job on my S200, and of course my SYMs. They're all basically the same with differences in the details.
First scooter ever n I'm already regretting buying it .......😖
