My CPI suv 125 looks nice, but it won't work properly,help

[EarthFromObse...]

Bought the bike about 8 weeks ago, but only did CBT on Friday, started the bike on Monday (it's in a mates garage because it's more secure, 1st opportunity to to start it was Monday). I know I should've tested it as soon as it was delivered, it just wasn't possible. Got a couple of problems, hope you can help.

1stly, it's a 4 stroke, 5 speed bike. Secondhand from a reputable eBay shop (100% positive rating over 8 years).

Initial problem is this, starts up in neutral but won't idle for long before it drops the revs too low and the engine cuts out. If we toy around and up the revs manually it's fine, but definitely not great to be up so high when idling.

Other problem, on a short ride up the road and back find major issues when clicking up to second and third, the bike starts revving through the roof, and doesn't stop even when completely rolling off the throttle, what's more, dispute the high revs, the wheels receive no extra power, initially I thought I was stuck in neutral, but not the case here. Got my mate to have ago too so deffo not my newbie-ness causing the issue (well, probably not anyway).

Could the above problems be explained by the choke lever being placed on the bike backwards to all expectation? I've got a couple of days before I head back to my mates so want to have a few things to try out when I'm there.

The seller says he had no problems starting and running the bike at his shop, so perhaps it's down to bike not being ridden in a while?

Any helpful advice welcome, I'd be so grateful, I promise.
____________________
I'm the great pretender, as in, I don't really know what I'm talking about, be kind please.

[P.addy]

The revs when cold... start the bike with choke on, it should idle around 2000rpm, maybe higher. After the engine has started, give it a good run, remove the choke at the end of your road and just ride it nicely for a few miles, get the revs going after about 5 minutes and get it really nice and warm. Set the idle to 1300rpm when the engine is nice and hot. I'd do a 10-15 minute ride.

With the riding issue, did you definitely give it a solid whack into gear rather than thinking you did and hitting a false neutral.