Hello,i've just rebuild my zenoah g230rc with,

25.5cc race ported big bore kit
1mm stuffer crank
lighten flywheel
race ported carb

problem is that it wont start,i have a spark and fuel going through,not sure about settings for the race carb,but tried all sorts,maybe its not sparking under compression,if so why not,i've ran out of ideas,i be very grateful of any help