Having listened to the comments of two young riders I would be inclined to agree with Tim Webster and Ben Powell. 500cc does seem to be a lot of HP for a someone less than 15 years old and 7st to handle. I thought I was the dogs b*ll*cks when I bought an RD250LC at the tender age of 16, but when I consider there are 13 year old boys riding 500cc racing machines my mind boggles. I can appreciate you need a certain amount of HP to get the rear wheel spinning and hence the bike turning, but in reality how much throttle do the younger riders really use? Perhaps a 250cc or 350cc class would be good for youth rider development. After all youth grasstrack riders use 125cc bikes up to 15 years of age (I think).