Engine trouble

[DUBDUB]

Hi, I have a 1988 gsxr250 and have had trouble with it running on all 4 cylinders. At the moment it is only running on 2, the 2 one the left side of the engine. I have checked the sparks and plugs are all clean and making a nice spark. I have checked to see if fuel is getting into all cylinders and it is so I have no idea what the problem could be. Can anyone help me with this problem?

[FROSTY]

mate do ya abc's
A motor needs air,fuel,compression and spark--its really that simple
If it wont run one or more components are missing