Is this digital?
If so then shots 1 and 4 are showing that you had dust on your camera sensor - which your going to need to clean off/have cleaned off.
As for composition I think the light has been bad for you - overcast can make for decent light since its not too strong, but several of yours shots are just lacking in colours from the light. You could try converting the shots to black and white (shot 1 for example)
Also what settings (ISO, aperture and shutter speed) did you use for these shots - to find this info go to the properties of the photo file and then click on the Details tab and scroll down. Also what camera and lens/s did you use
the sports bike seems to be out of focus on both.. try faster shutter.. though it will probably be hard.. none of them particularly jumped out at me, sorry
Number 2 would be great if you had someone facing away from the camera gazing off, but its a nice pic. Number 3 looks grainy, maybe too high of an Iso? Theres also a smudge on what is suppose to be in focus, maybe dust?
hmm thorpy - its better to either add the shots in a new post in the thread or start a new one = editing the first post with new shots just makes the thread hard to follow for new people (and really confused me when I saw differnet shots )