That's normal on a new engine when your struggling to start it, it's just passing the unburnt fuel through to the exhaust. Due to the shape of the pipe and the exit the fuel won't come out until you tip it over.
It doesn't help you trying to start it when the pipe's full of fuel obviously, but what are you doing when trying to start it? Basically with a new engine you're best off to warm it up as much as you can with a hair dryer to start off with it will help get it running quicker. Also when new it will foul the glow plug quite easily so you need to have 2 or 3 spares when first breaking it in.
If your struggling to turn it over to start it due to compression just back the glow plug out 1/4 to half a turn to easy the compression whilst you start it and then once it's ticking over tighten it up.
If you have a manual for the engine then check that the settings for the needle's are as per the break in settings. You may need to adjust them slightly leaner (screw them in) to get it running but try this in 1/8th to 1/4 turns, don't go mad.
Engines are always set rich to break them in, so even when running for the first 3-4 tanks you'll have neat fuel spitting out of the pipe but it should still run o.k.