peugeot vivacity has everything it needs, doesn't start

by now I've done a complete rebuild of the engine, changed the stator, cdi, spark plug, the wiring loom is good, the engine doesn't have cracks, compression is good, it is getting fuel, but still can't start, it's a 2005 vivacity AC. While doing the rebuild I discovered a crack in the crankcase which got welded up and fixed properly, before the rebuild it would try to start like every 20 cranks, now, with the exhaust off, every rev there's a tad bit smoke coming out of it, but it still doesn't want to start, the spark comes on at the right time, the plug isn't wet, nor dry, I can't seem to figure out what's the problem.
A friend of mine says he thinks it might be the ecu, because it is in some way connected to the ignition, but I'm really sceptical because by me, the main reason for it to be there is to calculate motorcycle hours which are displayed on the screen, haven't tested the ecu yet tho.
Any ideas?

 

no immobiliser

 

ECU is directly connected to the ignition. It's how it knows when to spark. Although I thought these have a CDI and not an ECU...

 

it has both, cdi and ecu, from what I thought the ecu just counted moto hours and such as the screen has those types of things, but on the other hand it is connected to the cdi directly
I'm thinking it might also be too much compression, cause the starter doesn't have enough strength to keep turning the engine over and over, only with the drills help it can crank like normal
I'll try putting in another type of fuel and see if it works, or spraying starter fluid into the carb

 

Ummm... If Its got a carb and a CDI it's not got an ECU....
An ECU is literally Engine Control Unit. It measures the mixture, rotational speed of crank/cam, spark timing, coolant temp, throttle position etc etc....
The CDI is just a box that tells the coil how much advance it should have at different engine speeds...
Try a totally new spark plug again...