Scooter sticks at 5k revs

Hi all I'm losing patience here
I bought a rieju rs 50 and pretty much been rebuilt as rear caliper snapped mounting on engine off so i got a used engine all good except the thing sticks at 5k most of the time and just keeps going. I have checked throttle cable. Cleaned carb. Adjusted idle. Checked all hoses getting really pissed off now any help be appreciated. Thanks Robbie ps i before the caliper snapped i did managed to do few miles on it old engine seemed ok

 

Hi,

What do you mean "sticks at 5k revs" exactly, like the engine just doesn't go past 5k at all or there's a slight pause etc... will help diagnose the issue.
Regards

 

Like when i rev its fine then suddenly it will stick at 5k and the back wheel will keep running until i turn off the scooter first few revs are fine then it starts

 

What year is the bike?