Best settings to shoot Go Karting

[GladstonePhotography]

Being new to Photography I went the other day to my local Kart track. Next Wednesday I am back there to shoot photographs of Kart Force. Kart Force is for Troops that are amputees some treble amputees but thanks to there founder who designed a was for then to drive Karts. Not to boar you all if you wish to know more visit.http://www.kartforce.org

OK took the Photos below as a test I am using an Olympus E-500 and a 17.5-45mm lens
As you can see photos are pixely. I shot in RAW Auto focus iso 800 and tried 1600 can anyone tell me if there is better settings I can use for next Wednesday.
Please try to keep your answers not to technical as I am still trying learn and not to sure about some technical terms yet put would be very gratefull for any help anyone can give me.

P1273799 by Wheelsforcharity, on Flickr


P1273796_edited-1 by Wheelsforcharity, on Flickr


P1273779 by Wheelsforcharity, on Flickr


P1273724 by Wheelsforcharity, on Flickr


P1273723 by Wheelsforcharity, on Flickr