Tjm1801

Is something in the mechanism gummed up? I've had cable operated carbs do similar things when people used WD40 to lube the cable or mechanism. WD40 is not a lubricant - it is a dispersant (which is what the D stands for) so it drive out lubrication. I use a spray with teflon in it and that seems to sort this kind of thing out.

It had brand new throttle cables because the last one rusted through I didn't lubricate it because of the Teflon coating inside, I don't think it's the throttle as it will allow me to back off the throttle with no problems.

Welcome to TMBF mate. .....pop over to the Newbies section and introduce yourself to the guys when you can. ......

Does the bike have an automatic choke?.........

Cheers and I will do, Noit has a manual choke although we had to strip it before as it was stuck. Should I check it again?

I'm really baffled by this problem,(it's probably an easy fix) but the bike is 2 stroke carburetted 50cc ,when the bike is cold ish it will rev to about 3k and then stick until I let off the throttle or change up a gear to wait for it to warm properly, then it will work no problems. I have recently put new reed valves in but I made sure to remove any air leaks as it was a problem before.