hi ladies and gents

hi im new to this forum but im hoping u can help me with my problem on my cbr400 rr. i brought this bike 2nd hand but she was running fine. scince then i have done alot work on it iv replaced the air filter had i found somone had cut one out of normal sponge lol,anyway she was running ok but never seemed right. well after we had some winter weather she doesnt seem to wana start iv checked fuel pump battery starter coil yet nothing she ticks over as you can hear it but thats it,but when we check the spark on plugs it very weak an seems be going to side of the plug an not between the gaps, so im wondering if its the ht leads or maybe the coils would this be best thing to try i have been looking for some 2nd hand ones but can only find nc29 not mine which is nc23 could i replace with the nc29, any help would be much apprecaited thanks.