Motorcycle Repair: 98/99 kawasaki ninja 250 no start, kawasaki ninja 250, timing curve

Question
hello I have just installed a 98 ninja 250 motor in to my 99 ninja 250 I am having a problem getting her to start the new motor has been rebuilt and has 1500 low miles on her it cranks and it backfires at times but wont start I know I am going to need a new battery soon I checked spark and I get spark but want to know what color a good spark should be I get a blue spark and the other thing I want to know is would I have to resync the carbs because they are synced to the 99 motor  thank you jason

Answer
Jason,Im probabbly going to throw you a curve but here goes. There are two different CDI,s avalable for this bike. The US and Canada version use CDI part# 21119-0010 and the Califonia version uses a #21119-0012. It has a differint timing curve and may make the system back fire so check everything to make sure its compatible. The carbs being synced may still need to happen but the bike should run without this just not as smooth.