As cossie says, heat it up with a hair drier to help things out.
For what its worth, the new engines Ive had have all been a right bugger to get going sometimes, so your not alone.
Basically dont give up, set the needles to factory if youve moved them(normally 2.5 turns out on the HSN and 1/2 to 1 turn in from flush on LSN) prime the engine, leave the glow warmer on there a few seconds, then give it a go.
If it fires up and idles but dies as you pull away, just wind the LSN out 1/16th and try again. Should be nice and rich when running in.
Dont allow too much fuel into the engine when starting as you can get hydraulic lock up and can bend rods and damage the engine, and dont fully extend the pull start as it can weaken the spring and break it. Short sharp pulls is all it should need.

Hope it helps.