Kx450f stalls

Hi

I Just finished the rebuild of my Kx450F -12 What i did was Striped it down to the frame clean and grease bearings and change the ones that was bad. All i did to the engine was a new piston and ned intake valves and camchain.

I checked the valve clearance twice and the timing.

Now i have put everything back together and when its warm it starts on the first kick and runs fine in neutrall but when you put 1st gear in it stalls really easy? If Im very sensitive on the gas/clutch i can get it roling but if i roll in idle speed in 1st and the hit it with gas it stalls on me??

If i run it with the choke out it works good but it revs a lot more.

So my guess is that it dosent get enough fule? Any other possible things that can fail or bee the reason?

Sorry for any misspelling hope you guys understand!