Nrg won't pull on anything over 1/4 throttle...help

Iv just put a new piston and rings, spark plug and top end gasket kit on my Nrg, i had bother starting and realised there was no vacuum pipe coming from the petrol tap! Got it sorted.

Now when I start it on the stand it revs for fun with no problem but when I took it for first spin up the street and it would not pull and bogged at about 20mph. 1/4 throttle was all I could move on.

70cc kit,
Standard delly carb,
TT exhaust

No air leaks anywhere.

Any advice????