Hey Rudy (not sure which one we are talking about now, lol)
Because it's for the kids
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Put the 8 Yr old on something like a Suzuki DS80 (short legged kid) or an Honda XR80 for a slightly bigger one but check eligibility for competition. Both these bikes are relatively docile for a newbie. There is little to be gained having an 8 yr old on an auto box if they are halfway clever.
Get them off to a good training school and once they are capable look at minikarna (motorcycling.com.au) before MX. Make the kids work their backsides off for the privilege of having a bike too otherwise they can turn into one of those ugly MX kids - don't they piss me off !!!
"Learn to ride smooth and speed will follow" - as for me I am still waiting for the speed part !!!
Dave Mac